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                                                                   EXHIBIT 10.33

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                  LOGO OF OAKBROOK TERRACE TOWER APPEARS HERE


                                  LEASE WITH

                           PLATINUM TECHNOLOGY, INC
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                                    TENANT


                                LEASING AGENTS

                     MIGLIN-BEITLER MANAGEMENT CORPORATION
                            181 West Madison Street
                                  Suite 3900
                            Chicago, Illinois 60602

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                                    LEASE
                                     FOR
                            OAKBROOK TERRACE TOWER


        This Lease is made and entered into at Oakbrook Terrace, Illinois, as of
the seventeenth (17th day of July_ _, 1996 by and between OAKBROOK TOWER LIMITED
PARTNERSHIP not individually, but solely and only as Trustee under a certain
Trust Agreement dated the 1st day of September, 1984, and known as Trust Number
1087600 (the "Landlord") and Platinum Technology Inc., a Delaware Corporation
(the "Tenant"), as follows

     1.   Lease of Premises. The Landlord hereby leases to the Tenant and the
Tenant hereby accepts the lease of the premises consisting of that certain
storage/warehouse space shown outlined in red or a heavy line on the plan
attached hereto as Exhibit A and incorporated herein by reference (the
"Premises") located on the Upper Level in the storage area of the office
building (the "Building") located on the real estate commonly known as Oakbrook
Terrace Tower, Oakbrook Terrace, Illinois (the "Real Estate"). The Building and
the Real Estate together with the vehicular drives, the above and below ground
parking facilities, and all other structures and improvements now or hereinafter
located upon the Real Estate are hereinafter sometimes collectively referred to
as the "Property." It is mutually agreed that the Premises contain 40,000
rentable square feet.

     2.   Term. The said lease of the Premises is for the term of six (6) years
and six (6) months commencing on that date (the "Commencement Date") which is
the earlier of (i) October 15, 1996, (ii) substantial completion of the Premises
with "Tenant's Work" (as defined in Section 14 of the Rider), or (iii) the date
upon which the Tenant utilizes any portion of the Premises for business purposes
(as opposed to occupancy and use of the Premises to make alterations therein),
and ending on the last day of the 78th month subsequent to the Commencement Date
(the "Term"), unless sooner terminated as hereinafter provided.

     3.   Rent. Tenant will pay to Landord's rental agents, MIGLIN- BEITLER
MANAGEMENT CORPORATION (the "Rental Agents"), at 181 West Madison Street, Suite
3900, Chicago, Illinois, 60602, or to such other persons or at such other places
as the Landlord may direct from time to time by written notice to the Tenant, in
coin or currency which at the time of payment is legal tender for the payment
of public and private debts in the United States of America, the aggregate of
the following, all of which are hereby declared to be "Rent."

          A.   The sum of       SEE SECTION 2 OF THE LEASE RIDER
                          ------------------------------------------------------
________________________________________________________________________________
____________________________________________DOLLARS($ __________________________
for each twelve-month period during the Term of this Lease, payable in advance
in equal monthly installments of _______________________________________________
                                        SEE SECTION 2 OF THE LEASE RIDER
________________________________________________________________________________
____________________________________________DOLLARS($ __________________________
each promptly on the first day of each and every calendar month during the Term
of this Lease (the "Base Rent").

          C.   Interest at the "Default Rate" from the due date of each payment
of Rent until paid. The phrase "Default Rate" means the lower of: (i) the
highest lawful rate, or (ii) a rate of interest equal to the sum of three
percent (3%) plus the "Prime Rate." The phrase "Prime Rate" means that rate of
interest most recently announced by the First National Bank of Chicago ("First")
as its prime rate or basic rate, changing



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simultaneously and automatically with each announced change by First in its
prime rate or its base rate, such change to be effective as of and on the date
announced by First as the effective date for the change in its said prime rate
or base rate. A certificate made by an officer of First stating its prime rate
or its base rate in effect on a certain day or prime rates or base rates in
effect during a certain period shall, for the purposes hereof, be conclusive
evidence of First's prime rate or rates or base rate or rates on said day or
such period, as may be stated in any such certificate. In the event First ceases
to use the term Prime Rate in setting a base rate of interest for commercial
loans, then the Prime Rate herein shall be determined by reference to the rate
used by First as a base rate of interest for commercial loans as the same shall
be designated by First to the Landlord.

          In the event the Term of this Lease commences on a day other than the
first day of a calendar month or ends on a day other than the last day of a
calendar month, the Rent for such month shall be prorated Tenant's covenant to
pay Base Rent, independent of every other covenant set forth in this Lease.

                                       2
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     5.   Security Deposit. As additional security for faithful and prompt
performance of its obligations hereunder Tenant has concurrently with the
execution of this Lease paid to Landlord's said Rental Agent the sum of $ NONE.
                                                                          ----
Said security deposit need not be segregated and may be applied by Landlord for
the purpose of curing any default or defaults of Tenant hereunder, in which
event, Tenant shall replenish said deposit in full by promptly paying to
Landlord on demand the amount so applied. Landlord shall not pay any interest on
said deposit, except as required by law. If Tenant has not defaulted hereunder
and Landlord has not applied said deposit to cure a default, or Landlord has
applied said deposit to cure a default and Tenant has replenished the same, then
said deposit, or such remaining portion thereof, shall be paid to Tenant after
the termination of this Lease. Said deposit shall not be deemed an advance
payment of Rent or a measure of Landlord's damages for any default hereunder by
Tenant.

     6.   Use. Tenant shall occupy and use the Premises for general storage and
warehouse purposes only. See Section 16 of the Lease Rider.

                                       3
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     8.   Tenant's Obligations.

          A.   Repairs. Except for ordinary wear and as otherwise provided in
this Lease, Tenant shall, at all times during the Term hereof, at its sole
expense, keep all Tenant's movable and removable fixtures located in or
appurtenant to the Premises in good order, repair and condition, and Tenant
shall promptly arrange with Landlord to have Landlord (or Landlord's agent) make
repairs of all other damages to the Premises and the replacement or repair of
all damaged or broken glass (including signs thereon), fixtures and
appurtenances (including hardware and heating, cooling, ventilating, electrical,
plumbing and other mechanical facilities in the Premises), with materials equal
in quality and class to the original materials damaged or broken, within any
reasonable period of time specified by Landlord. Landlord may, but shall not be
required to do so, enter the Premises at all reasonable times to make any
repairs, alterations, improvements or additions, including, but not limited to,
ducts and all other facilities for heating and air conditioning service, as
Landlord shall desire or deem necessary for the safety, preservation or
improvement of the Building, or as Landlord may be required to do by the
municipality in which the Building is located or by the order or degree of any
court or by any other proper authority. The cost of all repairs made by Landlord
to the Property which are made necessary as a result of misuse or neglect by
Tenant or Tenant's employees, invitees or agents or resulting from the Tenant's
failure to maintain and repair systems (including but not limited to HVAC,
plumbing and electrical systems), servicing the Premises in accordance with the
provisions contained in the Lease Rider,) shall be paid as additional Rent by
Tenant to Landlord within ten (10) business days of being billed for same. The
cost of all other repairs and replacements (except those caused by Tenant's
misuse or negligence and those relating to Tenant's movable fixtures) shall be
paid for by the Landlord. SEE SECTION 3 OF THE LEASE RIDER.

          C.   Doors to be Locked. Before leaving the Premises unattended,
Tenant shall close and securely lock all doors and shut off all utilities in the
Premises.

                                       4
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     D. Holding Over. Tenant shall pay to the Landlord for each day Tenant
retains possession of the Premises or any part thereof after termination hereof,
by lapse of time or otherwise, 150% the amount of the daily rental then required
by the terms hereof for the last monthly period prior to the date of such
termination and in addition if Tenant shall hold over in the Premises in excess
of thirty (30) days pay all damages sustained by Landlord by reason of such
retention, but acceptance by Landlord of rent after such termination shall not
constitute a renewal nor waive Landlord's right of reentry or any other right.

     E. Laws and Regulations. Tenant shall comply with all reasonable rules and
regulations Landlord may adopt from time to time for the protection and welfare
of the Building, the Property and its tenants and occupants, and comply with all
laws, ordinances, orders and regulations and with the directions of any public
officers authorized by law with respect to the Premises and the use and
occupancy thereof. SEE SECTION 24 OF THE LEASE RIDER

     F. Signs. Tenant shall not paint, display, inscribe or affix any sign,
trademark, picture, advertising, notice, lettering or direction on any part of
the outside or inside of the Building, except on the public hallways of the
Premises, and then only such name or names or matter and of such color, size,
style, character and material as shall be first approved by Landlord in writing.
Landlord reserves the right to remove any other matter, without notice to Tenant
and at the cost and expense of Tenant. SEE SECTION 5 OF THE LEASE RIDER

     G. Advertising. Tenant shall not use the name of the Building for any
purpose other than that of the business address of tenant, or use any picture or
likeness of the Building or "Oakbrook Terrace Tower" or any other name by which
the Building may from time to time be known, on any letterhead, envelope,
circular, notice, advertisement, container or wrapping material, without the
prior written consent of Landlord.

     H. Articles Sold. Tenant shall not exhibit, sell or offer for sale, rent or
exchange in the Premises or on the Property any article, thing or service except
those ordinarily embraced within the use of the Premises specified in Section 6
without the prior written consent of Landlord.

     I. Hazardous Materials. Tenant shall not use or permit to be brought into
or kept in the Premises or on the Property any inflammable oils or fluids, or
any explosive or other articles deemed hazardous to person or property. SEE
SECTION 25 OF THE LEASE RIDER

     J. Various Prohibited Uses. Tenant shall not carry on any mechanical
business without the prior written consent of Landlord; use the Premises for
housing, lodging or sleeping purposes; permit food to be brought into the
Premises for consumption therein, by anyone other than Tenant's employees,
business invitees and agents without the prior written consent of Landlord.
Landlord may in its sole discretion refuse such permission or impose any
conditions in granting it, and revoke it at will. Tenant shall not occupy or use
the Premises or permit the Premises to be occupied or used for any purpose, act
or thing which is in violation of any public law, ordinance or governmental
regulation or which may be dangerous to persons or property, or which may
invalidate or increase the amount of premiums for any policy of insurance
carried on the Building or covering its operation or violate the terms thereof;
provided, however, that if any additional amounts of insurance premiums are
caused by Tenant's occupancy or use of the Premises. Tenant shall pay to
Landlord said additional amounts. Tenant, at its sole expense, shall comply with
all rules, regulations and requirements of the Illinois Inspection and Rating
Bureau. Tenant shall not do or permit anything to be done upon the Premises, or
bring or keep anything thereon by its employees, agents and business invitees
which is in violation of rules, regulations or requirements of the City of
Oakbrook Terrace Fire Department, Illinois Inspection and Rating Bureau, Fire
Insurance Rating Organization, or any other similar authority having
jurisdiction over the Building. Tenant shall not use the Premises for housing
accommodations, for lodging or sleeping purposes or for any illegal purposes.
Tenant shall not at any time engage in the manufacture, sale, purchase, use or
gift of any spirituous, fermented, intoxicating or alcoholic liquors from the
Premises or property.

     K. Sound Devices. Tenant shall not place any radio or television
antenna aerial wires or other equipment on the roof or on or in any part of the
inside or outside of the Building other than the inside of the Premises; operate
or permit to be operated any musical or sound producing instrument or device
inside or outside the Premises which may be heard outside the Premises, and
which interferes with other tenants of the Building, operate any electrical
device which interferes with or impair radio or television broadcasting or
reception from or in the Building or elsewhere.

                                       5
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          L. Nuisances. Tenant shall not bring or permit to be in the Building
any bicycle or other vehicle, or dog (except in the company of a blind person)
or other animal: make or permit any noxious noise, vibration or odor to emanate
from the Premises: do anything therein tending to create, or maintain, a
nuisance: disturb, solicit or canvass any occupant of the Building.

          M. Cleanliness and Obstruction of Public Areas. Tenant shall take or
permit to be taken in or out of other entrances of the Building, or take or
permit on other elevators, any item normally taken in or out through the
trucking concourse or service doors or in or on freight elevators or, whether
temporarily, accidentally or otherwise, allow anything to remain in place or
store anything in, or obstruct in any way, any common area, passageway, exit,
stairway, elevator, shipping platform, or truck concourse. Tenant shall lend its
full cooperation to keep such areas free from all obstruction and move all
supplies, furniture and equipment as soon as received directly to the Premises
and move all such items and waste, other than waste customarily removed by
employees of the Building, being taken from the Premises, directly to the
shipping platform at or about the time arranged for removal therefrom.

          N. Overload Any Floor. Tenant shall not overload any floors.

          O. Defacing Premises. Tenant shall not do any or mark, paint, cut or
drill into, drive nails or screws into, or commits waste in any part of the
Premises or the Building, outside or inside, without the prior written consent
of Landlord. (If Tenant desires signal, communication, alarm or other utility or
service connections installed or changed, the same shall be made by and at the
expense of Tenant, with the approval and under direction of Landlord.)

          P. Alterations. *Tenant shall not make installations, alterations or
additions in or to the Premises without submitting plans and specifications to
Landlord and securing the prior written consent of Landlord in each instance.
Such work shall be done at the sole cost and expense of Tenant by employees of
or contractors employed by Landlord, or with Landlord's consent in writing given
prior to letting of contract, by contractors employed by Tenant, but in each
case, only under written contract previously approved in writing by Landlord,
and subject to all reasonable conditions Landlord may impose. All installations,
alterations and additions shall be constructed in a good and workmanlike manner
and only good grades of material shall be used, and shall comply with all
reasonable insurance requirements, and with all ordinances and regulations of
the City of Oakbrook Terrace or any department or agency thereof, and with the
requirements of all statutes and regulations of the State of Illinois or any
department or agency thereof. Tenant shall permit Landlord to supervise all
construction operations within the Premises. If alterations are made by Tenant's
contractors, Tenant shall furnish to Landlord prior to commencement thereof,
building permits and certificates of appropriate insurance, and upon completion
of any installation, alteration or addition. Contractor's Affidavits and full
and Final Waivers of Lien covering all labor and material expended and used.
Tenant shall hold Landlord harmless from all claims, costs, damages, liens and
expenses which may arise out of or be connected in any way with said
installations, alterations or additions.

     9.   Rights Reserved to Landlord. Landlord shall have the following rights
exercisable without notice and ** without liability to Tenant for damage or
injury to property, person or business (all claims for damage being hereby
released), and without effecting an eviction or disturbance or Tenant's use or
possession or giving rise to an claim for scroffs, or abatement of rent:

          A.  To change the name or street address of the Building.

          B.  To install and maintain signs on the exterior and interior of the
building (excluding the interior of the Premises) or anywhere on the Property.

          C.  To have passkeys to the Premises. SEE SECTION 4 OF THE LEASE RIDER

          D.  To decorate, remodel, repair, alter or otherwise prepare the
Premises for reoccupancy

* other than the initial improvements contemplated by Section 14 of the Lease
  Rider


** except as specifically provided in the Lease Rider

                                       6
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during the last six months of the Term hereof, if during or prior to such time
Tenant vacates the Premises, or any time after Tenant abandons the Premises.

          F.  To enter the Premises at reasonable hours to make inspections, or
to exhibit the Premises to prospective tenants, purchasers or others, or for
other reasonable purposes.

          G.  To have access to all mail chutes according to the rules of the
United States Post Office.

          H.  To require all persons entering or leaving the main entrance of
the Building during such hours as Landlord may from time to time reasonably
determine to identify themselves to a watchman by registration or otherwise and
to establish their right to leave or enter, and to exclude or expel any peddler,
solicitor or beggar at any time from the Premises or the Property.

          I.  To approve the location of heavy items in and about the Premises
and the Building and to require all such items and other office furniture and
equipment to be moved in and out of the Property and Premises only through the
loading dock and in all events at Tenant's sole risk and responsibility.

          J.  At any time or times, to decorate but not within the Premises and
to make, at its own expense, repairs, alterations, additions and improvements,
structural or otherwise, in or to the Premises, the Property or part thereof,
and to perform any acts related to the safety, protection or preservation
thereof, and during such operations to take into and through the Premises or any
part of the Property all material and equipment required and to close or
temporarily suspend operation of entrances, doors, corridors, elevators or other
facilities, provided that Landlord shall cause as little inconvenience or
annoyance to Tenant as is reasonably necessary in the circumstances, and shall
not do any act which permanently reduces the size of the Premises. Landlord may
do any such work during ordinary business hours and Tenant shall pay Landlord
for overtime and for any other expenses incurred if such work is done during
other hours at Tenant's request.

          K.  To do or permit to be done any work in or about the Premises or
 the Property or any adjacent nearby building, land, street or alley.

          L.  To grant to anyone the exclusive right to conduct any business or
render any service on the Property, provided such exclusive right shall not
operate to exclude Tenant from the use expressly permitted by Section 6 of this
Lease.

          M.  To close the Building at 8:00 p.m. or at such reasonable time as
Landlord may determine, subject, however, to Tenant's right to admittance under
such regulations as shall be prescribed from time to time by Landlord.

     10.  TELEPHONE, ELECTRIC AND OTHER SERVICES.

          A.  Tenant shall make arrangements directly with the telephone
companies servicing the Building for such telephone service in the Premises as
may be desired by Tenant. Tenant shall pay the entire cost of all telephone
charges, electricity consumed within the Premises, the installation of
electrical meters, maintenance of light fixtures and replacement of lamps,
bulbs, tubes, ballasts and starters.

          B.  If Tenant desires telegraphic, telephonic, burglar alarm, computer
installations or signal service (which service shall be at Tenant's sole
expense), Landlord shall, upon request, direct where and how all connections
and wiring for such service shall be introduced and run. In the absence of such
directions, Tenant shall make no borings, cutting or install any wires or cables
in or about the Premises.

          C.  Tenant covenants and agrees that Landlord shall in no event be
liable or responsible to Tenant for any loss, damage or expense which Tenant may
sustain or incur if either the quality or character of electrical service is
changed or is no longer suitable for Tenant's requirements. Tenant covenants and
agrees that at all times its use of electric current shall never exceed 5.5
watts per rentable square foot in the office portion of the Premises and 2.0
watts per rentable square foot in the warehouse portion of the Premises, and
also that it shall make no alterations or additions to the electric equipment
and/or appliances without the prior written consent of Landlord in each
instance.

     11.  Landlord's Title. Landlord's title is and always shall be paramount to
the title of Tenant. Nothing herein contained shall empower Tenant to do any act
which can, shall or may encumber the title of Landlord.

                                       7
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     12.  Quiet Enjoyment. Subject to the provisions of this Lease, Landlord
covenants that Tenant, on paying the Rent and performing the covenants of this
Lease on its parts to be performed, shall and may peaceably and quietly have,
hold and enjoy the Premises for the Term of this Lease.
     SEE LEASE RIDER SECTION 19.

     14.  Condition of Premises*. Tenant's taking possession shall be conclusive
evidence that the Premises were then in good order, repair and satisfactory
condition. Except as may be set forth in the Lease Rider attached hereto, no
promise to Landlord to alter, remodel, improve, repair, decorate or clean the
Premises or any part thereof, and no representation respecting the condition of
the Premises or the Property has been made to Tenant by Landlord except as made
herein.

     15.  Termination. At the termination of this Lease, by lapse of time or
otherwise:

          A.   Surrender of Keys. Tenant shall surrender all keys of the
Premises to Landlord and make known to Landlord the explanation of all
combination locks remaining on Premises.

          B.   Return of Premises. Tenant shall return to Landlord the Premises
and all equipment and fixtures of Landlord in as good a condition and state of
repair as when Tenant originally took possession subject, however, to (a) the
provisions of Paragraphs C and D of this Section 15; (b) ordinary wear and loss
or damage by fire; or (c) other casualty covered in Section 17 hereof, failing
which Landlord may restore the Premises, equipment and fixtures to such
condition and state of repair and Tenant shall, within ten (10) business days of
demand, pay to Landlord the reasonable cost thereof.

          C.   Removal of Additions. All installations, additions, hardware,
nontrade fixtures and improvements temporary or permanent, except movable
furniture and equipment belonging to Tenant, in or upon the Premises, whether
placed there by Tenant or Landlord, shall be Landlord's property and shall
remain upon the Premises, all without compensation, allowance or credit to
Tenant; provided, however, that if prior to such termination or within ten
business days thereafter Landlord so directs by notice, Tenant shall promptly
remove the installations, additions, hardware, non-trade fixtures and
improvements, placed in or upon the Premises by Tenant and designated in the
notice, failing which Landlord may remove the same and Tenant shall, upon
demand, pay to Landlord the reasonable cost of such removal and of any necessary
restoration of the Premises. SEE LEASE RIDER SECTION 18.

          D.   Floor Covering. Tenant may remove any floor covering entirely
paid for and laid by Tenant, provided Tenant (a) removes all fastenings, paper,
glue, bases and other vestiges thereof and restores the floor surface to its
previous condition, or (b) pays to Landlord, upon demand, the cost of

*  Except for landlord's obligation to complete Landlord's Work (as defined in
   Section 11 of the Lease Rider),

** SEE LEASE RIDER SECTION 18

                                       8
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restoring the floor surface condition.

          E.   Property Presumed Abandoned. All fixtures, installations, and
personal property belonging to Tenant not removed from the Premises upon
termination of this Lease and not required by Landlord to have been removed as
provided in Paragraph C of this Section 15, shall be conclusively presumed to
have been abandoned by Tenant and title thereto shall pass to Landlord under
this Lease as by a Bill of Sale. See Section 20 of the Lease Rider.

     16.  Assignment and Subletting. Tenant shall not, without the prior written
consent of Landlord in each instance: (i) assign, transfer, mortgage, pledge,
hypothecate or encumber, or subject to or permit to exist upon or be subjected
to any lien or charge, this Lease or any interest under it; (ii) allow to exist
or occur any transfer of or lien upon this Lease or the Tenant's interest herein
by operation of law; (iii) sublet the Premises or any part thereof; or (iv)
permit the use or occupancy of the Premises or any part thereof for any purpose
not provided for under Section 6 of this Lease or by anyone other than the
Tenant and Tenant's employees. In no event shall this Lease be assigned or
assignable by voluntary or involuntary bankruptcy proceedings or otherwise, and
in no event shall this Lease or any rights or privileges hereunder be an asset
of Tenant under any bankruptcy, insolvency or reorganization proceedings.

          Tenant shall, by notice in writing, advise Landlord of its intention
from, on and after a stated date (which shall not be less than sixty (60) days
after date of Tenant's notice) to assign or transfer its interest as Tenant in
this Lease, or sublet any part or all of the Premises for the balance or any
part of the Term, and in such event, Landlord shall have the right to be
exercised by giving written notice to Tenant thirty (30) days after receipt of
Tenant's notice, to recapture the space described in Tenant's notice and such
recapture notice shall, if given, cancel and terminate this Lease with respect
to the space therein described as of the date stated in Tenant's notice,
Tenant's said notice shall state the name and address of the proposed subtenant
and a true and complete copy of the proposed sublease shall be delivered to
Landlord with said notice. If Tenant's notice shall cover all of the Premises,
and Landlord shall give the aforesaid recapture notice with respect thereto, the
Term of this Lease shall expire and end on the date stated in Tenant's notice as
fully and completely as if that date had been herein definitely fixed for the
expiration of the Term. If, however, this Lease be canceled pursuant to the
foregoing with respect to less than the entire Premises, the Rent and Rent
Adjustments herein reserved shall be adjusted on the basis of the number of
square feet retained by Tenant in proportion to the number of square feet
contained in the Premises, as described in this Lease, and this Lease, as so
amended, shall continue thereafter in full force and effect. If Landlord, upon
receiving Tenant's said notice with respect to any such space, shall not
exercise its right to cancel as aforesaid, Landlord will not unreasonably
withhold its consent to Tenant's assignment as aforesaid or subletting the space
covered by its notice.

          Any subletting or assignment hereunder shall not release or discharge
Tenant of or from any liability, whether past, present or future, under this
Lease, and Tenant shall continue fully liable thereunder. The subtenant or
subtenants or assignee shall agree to comply with and be bound by all of the
terms, covenants, conditions, provisions and agreements of this Lease to the
extent of the space sublet or assigned, and Tenant shall deliver to Landlord
promptly after execution, an executed copy of each such sublease or assignment
and an agreement of compliance by each such subtenant or assignee.

          If Tenant shall assign or transfer its interest in this Lease or
sublet the Premises having first obtained Landlord's consent at a rental in
excess of the rent due and payable by Tenant under the provisions of Sections 3
and 4 of this Lease 50% of said excess rent after deducting therefrom Tenant's
actual and reasonable costs incurred in relation to such assignment or transfer
shall be paid to the Landlord.

          Any sale, assignment, mortgage, transfer or subletting of this Lease
which is not in compliance with the provisions of this paragraph shall be of no
effect and void.

          The Landlord may assign this Lease and thereafter shall not be liable
hereunder; provided, that the Landlord's assignee shall assume the Landlord's
obligations hereunder. No assignee, sublettee or licensee of Tenant shall be
entitled to exercise or receive the benefits of any option or right contained in
this Lease or any rider or future amendment hereto granting the Tenant the
right:

     (1)  to extend or renew the Term;
     (2)  to lease any additional space in the Building;
     (3)  to utilize any reserved or underground parking space; or
     (4)  to utilize any health club memberships.

     17.  Untenantability. In the event (a) Premises are made untenantable by
fire or other casualty and Landlord shall decide not to restore or repair same,
or (b) the Building is so damaged by fire or other casualty that Landlord shall
decide to demolish or not rebuild the same, then, in any of such events,
Landlord shall have the right to terminate this Lease by notice to Tenant within
ninety (90) days after the

                                       9
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date of such fire or other casualty and the Rent shall be apportioned on a per
diem basis and paid to the date of such fire or other casualty. In the event the
Premises are made untenantable by fire or other casualty and Landlord shall
decide to rebuild and restore the same, this Lease shall not terminate and
Landlord shall repair and restore the Premises at Landlord's expense and with
due diligence, subject, however, to (i) reasonable delays for insurance
adjustments and (ii) delays caused by forces beyond Landlord's control, and the
Rent shall abate on a per diem basis the period or reconstruction and repair.

          In the event the Premises are partially damaged by fire or other
casualty but are not made wholly untenantable, then Landlord shall, except
during the last year of the term hereof proceed with all due diligence to repair
and restore the Premises, subject, however, to (i) reasonable delays for
insurance adjustments, and (ii) delays caused by forces beyond Landlord's
control. In such event, the Rent shall abate in proportion to the nonusability
of the Premises during the period while repairs are in progress. If the Premises
are made partially untenantable as aforesaid during the last year of the Term
hereof, as said Term may have been extended or renewed either Tenant or Landlord
shall have the right to terminate this Lease as of the date of fire or other
casualty, in which event, the Rent shall be apportioned on a per diem basis and
paid to the date of such fire or other casualty.

     18.  Rights and Remedies of Landlord. All rights and remedies of Landlord
herein enumerated shall be cumulative and none shall exclude any other right or
remedy allowed by law.

          A.   If any voluntary or involuntary petition or similar pleading
under any section or sections of any bankruptcy act shall be filed by or against
Tenant, or any voluntary or involuntary proceeding in any court or tribunal
shall be instituted to declare Tenant insolvent or unable to pay Tenant's debts,
or Tenant makes an assignment for the benefit of its creditors, or a trustee or
receiver is appointed for Tenant or for the major part of Tenant's property,
then and in any such event, Landlord may, if Landlord so elects, but not
otherwise, and with or without notice of such election, and with or without
entry or other action by Landlord, forthwith terminate this Lease, and,
notwithstanding any other provisions of this Lease, Landlord shall forthwith
upon such termination be entitled to recover damages in an amount equal to the
then present value of the Rent specified in Section 3 and 4 of this Lease for
the residue of the stated term hereof, less the fair rental value of the
Premises for the residue of the stated term.

          B.   If Tenant defaults in the prompt payment of Rent and such default
shall continue for five or more days after the Tenant's receipt of written
notice that the same be due and payable or in the performance or observance of
any other provision of this Lease and such other default shall continue for ten
or more business days after notice thereof shall have been given to Tenant, or
if the leasehold interest or Tenant be levied upon under execution or attached
by process of law, or if Tenant abandons the Premises, then and in any such
event, Landlord, if it so elects, with or without notice or demand, forthwith,
or at any time thereafter while such default continues, either may terminate
Tenant's right to possession, without terminating this Lease, or may terminate
this Lease. If the term of any lease, other than this Lease, made by Tenant for
any premises in the Building shall be terminated or terminable after the making
of this Lease because of any default by Tenant under such other lease, such fact
shall empower Landlord, at Landlord's sole option, to terminate this Lease by
notice to Tenant SEE SECTION 29 OF THE LEASE RIDER.

          C.   Upon termination of this Lease, whether by lapse of time or
otherwise, or upon any termination of Tenant's right to possession without
termination of this Lease, Tenant shall surrender possession and vacate the
Premises immediately, and deliver possession thereof to Landlord and hereby
grants to Landlord full and free license to enter into and upon the Premises in
such event with or if and only if Tenant has abandoned the Premises without
process of law and to repossess Landlord of the Premises as of Landlord's former
estate and to expel or remove Tenant and any others who may be occupying or
within the Premises and to remove any and all property therefrom, using such
force as may be necessary, without being deemed in any manner guilty of
trespass, eviction, forcible entry or detainer, or conversion of property, and
without relinquishing Landlord's rights to Rent or any other right given to
Landlord hereunder or by operation of law, Tenant expressly waives the service
of any demand for payment of Rent or for possession and the service of any
notice of Landlord's election to terminate this Lease or to reenter the
Premises, including any and every form of demand and notice prescribed by any
statute or other law, and agrees that the simple breach of any convenant or
provision of this Lease by Tenant shall, (after the expiration of any, if any
applicable notice and cure period provided herein) of itself, without the
service of any notice or demand whatsoever, constitute a forcible detainer by
Tenant of the Premises within the meaning of the statutes of the State of
Illinois.

          D.   If Tenant abandons the Premises or otherwise entitles Landlord so
to elect, and if Landlord elects to terminate Tenant's right to possession only,
without terminating this Lease, Landlord

                                      10
<PAGE>

may, at Landlord's option, enter upon the Premises, remove Tenant's signs and
other evidences of tenancy, and take and hold possession thereof as provided in
Paragraph C of this Section 18, without such entry and possession terminating
this Lease, or releasing Tenant, in whole or in part, from Tenant's obligation
to pay the Rent hereunder for the full term, and in any such case, Tenant shall
pay to Landlord within ten (10) days after receipt of a notice from Landlord
advising the Tenant that Landlord has elected to accelerate the Rent, a sum
equal to the present value of entire amount of the Rent specified in Section 3
of this Lease for the residue of the stated term plus any other sums then due
hereunder. Upon and after entry into possession without termination of this
Lease, Landlord shall use reasonable efforts to mitigate its damages by
attempting to relet the Premises or any part thereof for the account of Tenant
to any person, firm or corporation other than Tenant for such rent, for such
time and upon such terms as Landlord in Landlord's sole discretion shall
determine, and Landlord shall not be required to accept any tenant offered by
Tenant or to observe any instructions given by Tenant about such reletting. In
any such case, Landlord may make repairs, alterations and additions in or to the
Premises, and redecorate the same to the extent deemed by Landlord reasonably
necessary or desirable, and Tenant shall, upon demand, pay the cost thereof,
together with Landlord's expenses of the reletting. If the consideration
collected by Landlord upon any such reletting for Tenant's account is not
sufficient to pay the full amount of unpaid Rent reserved in this Lease,
together with the reasonable cost of repairs, alterations, redecorating and
Landlord's reasonable expenses, Tenant shall pay to Landlord the amount of any
deficiency, upon demand. If the consideration so collected from any such
reletting together with the present value of Rent payment, if any made by Tenant
is more than sufficient to pay the full amount of the rent reserved herein,
together with the reasonable costs and expenses of Landlord, Landlord, at the
end of the stated term of this Lease, shall account for and pay over the surplus
to Tenant.

          E.   Any and all property, which may be removed from the Premises by
Landlord pursuant to the authority of this Lease or of law, to which Tenant is
or may be entitled, may be handled, removed or stored in a commercial warehouse
or otherwise by Landlord at the risk, cost and expense of Tenant, and Landlord
shall in no event be responsible for the value, preservation and safekeeping
thereof. Tenant shall pay to Landlord, upon demand, any and all expenses
incurred in such removal and all storage charges against such property so long
as the same shall be in Landlord's possession or under Landlord's control. Any
such property of Tenant not removed from the Premises or retaken from storage by
Tenant within thirty (30) days after the end of the term, however terminated,
shall be conclusively deemed to have forever abandoned by Tenant.

          F.   Tenant shall pay all Landlord's costs, charges and expenses,
including the fees of counsel, agents and others retained by Landlord, incurred
in enforcing Tenant's obligations hereunder or incurred by Landlord in any
litigation, negotiation or transaction in which Tenant causes Landlord, without
Landlord's fault, to become involved or concerned. SEE SECTION 30 OF THE LEASE
RIDER

          G.   If Tenant violates any of the terms and provisions of this Lease,
or defaults in any of its obligations hereunder, other than the payment of Rent
or other sums payable hereunder, such violations may be restrained or such
obligation enforced by injunction.

     19.  Eminent Domain. If the Property, or any portion thereof which includes
a substantial part of the Premises, shall be taken or condemned by any competent
authority for any public use or purpose, the term of this Lease shall end upon,
and not before, the date when the possession of the part so taken shall be
required for such use or purpose, and without apportionment of the award. Rent
shall be apportioned as of the date of such termination. If any condemnation
proceeding shall be instituted in which it is sought to take or damage any part
of the Property, or if the grade of any street or alley adjacent to the Property
is changed by any competent authority and such change of grade makes it
necessary or desirable to remodel

                                      11
<PAGE>

the Property to conform to the changed grade, Landlord shall have the right to
cancel this Lease upon not less than ninety (90) days notice prior to the date
of cancellation designated in the notice. No money or other consideration shall
be payable by Landlord to Tenant for said cancellation, and the Tenant shall
have no right to share in the condemnation award or in any judgment for damages
caused by said eminent domain proceeding.

     20.  Subordination or Superiority of This Lease. The rights and interest of
Tenant under this Lease shall be subject and subordinate to any mortgage or
trust deed that exists now or may hereafter be placed upon the Building or Real
Estate or Property and to any and all advances to be made thereunder, and to the
interest thereon, and all renewals, replacements and extensions thereof. Any
mortgagee or trustee may elect to give the rights and interest of Tenant under
this Lease priority over the lien of its mortgage or trust deed. In the event of
such election and upon notification by such mortgagee or trustee to Tenant to
that effect, the right and interest of Tenant under this Lease shall be deemed
to have priority over, the lien of said mortgage or trust deed, whether this
Lease is dated prior to or subsequent to the date of said mortgage or trust
deed. Tenant shall promptly execute and promptly deliver whatever instruments
may be required for such purposes, and in the event Tenant fails so to do within
ten (10) days after demand in writing, Tenant shall be deemed in default
hereunder SEE SECTION 31 OF THE LEASE RIDER.

     21.  Sprinklers. If the "sprinkler system" installed with in the Premises
or any of its appliances shall be damaged or injured or not in proper working
order by reason of any act or omission of Tenant, Tenant's agents, servants,
employees, licensees or visitors. Tenant shall forthwith restore the same to
good working condition at its own expense; and if the Board of Fire Underwriters
or Fire Insurance Exchange or any bureau, department or official of the state or
city government, requires or recommends that any changes, modifications,
alterations or additional sprinkler heads or other equipment be made or supplied
by reason of a change in Tenant's business or the location of partitions, trade
fixtures, or other contents of the Premises, or if any such changes,
modifications, alterations, additional sprinkler heads or other equipment,
become necessary to prevent the imposition of a penalty or charge against the
full allowance for a sprinkler system in the fire insurance rate as fixed by
said Exchange, or by any fire insurance company. Tenant shall, at Tenant's
expense, promptly make and supply such changes, modifications, alterations,
additional sprinkler heads or other equipment.

     22.  Notice. In every instance where it shall be necessary or desirable for
Tenant to serve any notice or demand upon Landlord, such notice or demand shall
be sent by United States Registered or Certified Mail, postage prepaid,
addressed to Landlord at the place where rental under this Lease is then being
paid. Any notice or demand to be given by Landlord to Tenant shall be effective
if mailed or delivered to the Premises and to Tenant at 1815 S. Meyers Road,
Oakbrook Terrace, Illinois 60181, Attn.: Legal Department, or to such other
address as may appear on the records of Landlord. Notice mailed as aforesaid
shall be conclusively deemed to have been served at the close of the second
business date following the date said notice was mailed.

     23.  Successors and Assigns. Each provision hereof shall extend to and
shall, as the case may require, bind and inure to the benefit of Landlord and
Tenant and their respective heirs, legal representatives, successors and
assigns, provided that this Lease shall not inure to the benefit of any
assignee, heir, legal representative, transferee or successor of Tenant except
upon the prior written consent or election of Landlord or as provided in Section
16 of the Lease Rider.

     The term "Landlord," as used in this Lease, means only the owner, or the
mortgagee in possession, for the time being, of the Property (or the owner of a
lease of the Building or of the Real Estate and the Building) of which the
Premises form a part, so that in the event of any sale or sales of said Real
Estate and the Building or of said Lease, or in the event of a lease of the
Building, or of the Real Estate and the Building, landlord shall be and hereby
is entirely free and relieved of all covenants and obligations of Landlord
hereunder, and it shall be deemed and construed without further agreement
between the

                                      12
<PAGE>

parties of their successors in interest, or between the parties and the
purchaser at any such sale, or the said lessee of the Building, or of the
Real Estate and the Building, that the purchaser or the lessee of the Building
has assumed and agreed to carry out any and all covenants and obligations of
Landlord hereunder whether past, present or future.

     25.  Insurance.  SEE SECTION 22 OF THE LEASE RIDER

          (a)  Landlord and Tenant agree to have all property insurance policies
which may be carried by either of them endorsed with a clause providing that any
release from liability of or waiver of claim for recovery from the other party
entered into in writing by the insured thereunder prior to any loss or damage
shall not affect the validity of said policy or the right of the insured to
recover thereunder. Without limiting any release or waiver of liability or
recovery contained in any other paragraph of this Lease but rather in
confirmation and furtherance thereof, Landlord and Tenant each hereby waive any
and every claim for recovery from the other for any and all loss of or damage to
the Property or to the contents thereof, which loss or damage is covered by
valid and collectible fire and extended coverage insurance policies, to the
extent that such loss or damage is recoverable under said insurance policies.
Inasmuch as this mutual waiver will preclude the assignment of any such claim by
subrogation (or otherwise) to an insurance company (or any other person),
Landlord and Tenant each agree to give to each insurance company which has
issued, or in the future may issue, to its policies of fire and extended
coverage insurance, written notice of the terms of this mutual waiver, and to
have said insurance policies properly endorsed, if necessary to prevent the
invalidation of said insurance coverage by reason of said waiver.

          (b)  At all times during the Term of this Lease, Tenant shall at its
sole cost and expense maintain in full force and effect insurance protecting
Tenant and Landlord and Landlord's beneficiaries and their respective agents and
any other parties designated by Landlord from time to time, with terms,
coverages and in companies at all times reasonably satisfactory to Landlord and
with such increases in limits as Landlord may, from time to time, reasonably
request and require of all other similarly situated tenants. Initially, such
coverage shall be in the following amounts:

               (i)  Comprehensive General Liability Insurance, including
     Contractual Liability insuring the indemnification provisions contained in
     this Lease, with limits of not less than Two Million Dollars
     ($2,000,000.00) combined single limit per occurrence for Bodily Injury,
     Death and Property Damage. The Comprehensive General Liability policy shall
     include as additional insureds the Landlord, its beneficiaries and their
     respective agents, with a severability of interest endorsement.

               (ii) Insurance against (A) "All Risks" of physical loss coverage,
     movable fixtures, office equipment, furniture, trade fixtures, merchandise
     and all other items of Tenant's property on the Premises, and (B) loss of
     use of the Premises.

          Tenant shall, prior to the commencement of the Term hereof and prior
to the expiration of any policy, furnish Landlord certificates evidencing that
all required insurance is in force and providing that such insurance may not be
cancelled or changed without at least thirty (30) days' prior written notice to
Landlord and Tenant (unless such cancellation is due to nonpayment of premiums,
in which event ten (10) days' prior written notice shall be provided).

     26.  Miscellaneous.

          A.   Force Majeure.  Wherever there is provided in this Lease a time
limitation for performance by the Landlord or Tenant of any construction,
repair, maintenance or service, the time provided for shall be extended for as
long as and to the extent that delay in compliance with such limitation is due
to an act of God, strikes, governmental control or other factors beyond the
reasonable control of the Landlord or Tenant. The provisions hereof shall not
apply to the determination of the Commencement Date.

          B.   If any provision of this Lease or application to any party or
circumstances shall be determined by any court of competent jurisdiction to be
invalid and unenforceable to any extent, the remainder of this Lease or the
application of such provision to such person or circumstances, other than those
as to which it is so determined invalid or unenforceable to any extent, shall
not be affected thereby, and each provision hereof shall be valid and shall be
enforced to the fullest extent permitted by law.

          C.   The headings of sections are for convenience only and do not
define, limit or construe the contents of such sections or subsections.
References made in this Lease to numbered sections and subsections shall refer
to the numbered sections or subsections of this Lease, unless otherwise
indicated.

          D.   The Lease is to be executed in copies, each of which executed
copy shall constitute an original.  In the event of a conflict between the
provisions of any original lease with the provisions of any other original
lease, then in such event, the provisions of Landlord's original lease will
govern and control.

          E.   Each of the parties agrees, at the request of the other, to
execute such instruments or documents as any party may reasonably request,
acknowledging: the date of Completion of the Premises; the date of acceptance of
possession of the same; the date of commencement of rentals; the commencement of
the term; the commencement and expiration dates of this Lease; the Taxes and

                                      13
<PAGE>

Consumer Price Index for any Lease Year; the Estimated Rent Adjustment Payments
for any Lease Year; the number of rentable square feet demised to the Tenant;
Annual Base Rental amount; and the compliance or noncompliance by any party with
any of the terms or provisions of this Lease: and to evidence such other or
further matters as may be so reasonably requested.

          F.  Tenant represents that except for Stein & Company and
Miglin-Beitler Management Corporation, it has not dealt with any real estate
broker in connection with this Lease and, to its knowledge, no broker other than
Stein & Company and Miglin-Beitler Management Corporation initiated or
participated in the negotiation of this Lease, submitted or showed the Premises
to Tenant or is entitled to any commission in connection with this Lease. Tenant
hereby indemnifies, defends, and holds Landlord harmless from and against any
and all claims of any real estate broker for commissions in connection with this
Lease. SEE SECTION 23 OF THE LEASE RIDER.

          G.   No receipt of money by Landlord from Tenant after the termination
of this Lease, the service of any notice, the commencement of any suit or final
judgment for possession shall reinstate, continue or extend the term of this
Lease or affect any such notice, demand, suit or judgment.

          H.   No waiver of default of Tenant or Landlord shall be implied, and
no express waiver shall affect any default other than the default specified in
such waiver and that only for the time and to the extent therein stated.

          I.   Clauses, plats and riders, if any signed by Landlord and Tenant
and endorsed on or affixed to this Lease are part hereof and in the event of
variation or discrepancy, and duplicate original hereof, including such clauses,
plats and riders, if any, held by Landlord shall control.

          J.   Submission of this instrument for examination or signature by
Tenant does not constitute a reservation of or option for lease, and it is not
effective as a lease or otherwise until execution and delivery by both Landlord
and Tenant.

          K.   Wherever the consent of either Landlord or Tenant is required by
the provisions of this Lease, such party shall not unreasonably withhold or
delay such consent.

          27.  Estoppel Certificates. The parties hereto agree that, from time
to time upon not less than ten days prior request a statement in writing
certifying; (i) that this Lease is unmodified and in full force and effect (or
if there have been modifications that the Lease, as modified, is in full force
and effect); (ii) the dates to which Rent and other charges have been paid; and
(iii) that the Landlord and Tenant are not in default under any provision of
this Lease, or, if in default, the nature thereof in detail, it being intended
that any such statement may be relied upon by any prospective purchaser or
tenant of the Property, any mortgagees or prospective mortgagees thereof, or any
prospective assignee of any mortgage thereof. The parties shall execute and
deliver whatever instruments may be required for such purposes, and in the event
either party fails so to do within twenty (20) days after demand in writing,
such party shall be considered in default under this Lease.

          28.  Exculpatory Provisions. It is expressly understood and agreed by
and between the parties hereto, anything to the contrary notwithstanding, that
each and all of the warranties, indemnities, representations, covenants,
undertakings and agreements herein made on the part of the Trustee while in form
purporting to be the warranties, indemnities, representations, covenants,
undertakings and agreements of said Trustee are nevertheless each and every one
of them, made and intended not as personal warranties, indemnities,
representations, covenants, undertakings and agreements by the Trustee or for
the purpose or with the intention of binding said Trustee personally, but are
made and intended for the purpose of binding only that portion of the trust
property specifically described herein, and this instrument is executed and
delivered by said Trustee not in its own right, but solely in the exercise of
the powers conferred upon it as such Trustee; and that no personal liability or
personal responsibility is assumed by nor shall at any time be asserted or
enforceable against chicago Title and Trust Company, on account of this
instrument or on account of any warranty, indemnity, representation, covenant or
agreement of the said Trustee in this instrument contained, either expressed or
implied, all such personal liability, if any, being expressly waived and
released.

                                      14
<PAGE>

          29.  Unrelated Business Income. (a) Landlord shall have the right at
any time and from time to time to unilaterally amend the provisions of this
Lease, if Landlord is advised by its counsel that all or any portion of the
monies paid by Tenant to Landlord hereunder are, or may be deemed to be,
unrelated business income within the meaning of the United States Internal
Revenue Code or regulations issued thereunder, and Tenant agrees that it will
execute all documents or instruments necessary to effect such amendment or
amendments, provided that no such amendment shall result in Tenant having to pay
in the aggregate more money on account of its occupancy of the Premises under
the terms of this Lease, as so amended, and provided further that no such
amendment shall result in Tenant receiving less services than it is presently
entitled to receive under this Lease, nor services of a leasser quality.

          (b)  Any services which Landlord is required to furnish pursuant to
the provisions of this Lease may at Landlord's option, be furnished from time to
time, in whole or in part, by employees of Landlord or Landlord's beneficiaries,
the managing agent of the Real Property or its employees or by one or more third
persons hired by Landlord. Landlord's beneficiaries or the managing agent of the
Real Property, Tenant agrees that upon Landlord's written request it will enter
into direct agreements with the managing agent of the Real Property or other
parties designated by Landlord for the furnishing of any such services required
to be furnished by Landlord hereunder, in form and content approved by Landlord;
provided, however, that no such contract shall result in Tenant having to pay in
the aggregate more money on account of its occupancy of the Premises under the
terms of this Lease, and provided further that no such contract shall result in
Tenant receiving less services than it is presently entitled to receive under
this Lease, nor services or a lesser quality.

     IN WITNESS WHEREOF, this instrument has been duly executed by the parties
hereto, as of the date first above written.

LANDLORD                                     TENANT

OAKBROOK TOWER LIMITED PARTNERSHIP           PLATINUM TECHNOLOGY, INC. a
By: M&M Realty Corporation,                  Delaware corporation
    General Partner

BY Roland V. Siegl                           BY /s/ M. Cullinane
 ---------------------------------             ----------------------------
 Its     V.P.                                 Its  EXECUTIVE VICE PRESIDENT
    ------------------------------                 CHIEF FINANCIAL OFFICER
                                                 --------------------------

ATTEST Michael Strone                        ATTEST  /s/ Michael C. Wyatt
      ----------------------------                 ------------------------
      Its      Secretary                           Its VICE PRESIDENT AND
         -------------------------                     GENERAL COUNSEL
                                                       --------------------

                                      15
<PAGE>

                          LANDLORD'S ACKNOWLEDGEMENT

STATE OF CONNECTICUT )
                     )  SS
COUNTY OF FAIRFIELD  )

     I, the undersigned, a Notary Public in and for the County and State
aforesaid, DO HEREBY CERTIFY, that the above named Assistant Vice President and
Assistant Secretary of the OAKBROOK TOWER LIMITED PARTNERSHIP, Grantor,
personally known to me to be the same persons whose names are subscribed to the
foregoing instrument as such Assistant Vice President and Assistant Secretary
respectively, appeared before me this day in person and acknowledged that they
signed and delivered the said instrument as their own free and voluntary act and
as the free and voluntary act of said Company for the uses and purposes therein
set forth; and the said Assistant Secretary then and there acknowledged that
said Assistant Secretary, as custodian of the corporate seal of said Company,
caused the corporate seal of said Company to be affixed to said instrument as
said Assistant Secretary's own free and voluntary act and as the free and
voluntary act of said Company for the uses and purposes therein set forth.

                             Given under my hand and Notarial Seal this 2nd day
                             of August 1996.

                                                  [SEAL]

                                 /s/ Corinne Basta
                             --------------------------------------------------

                                      16
<PAGE>

                           TENANT'S ACKNOWLEDGEMENT

STATE OF ILLINOIS  )
                   )  SS
COUNTY OF DUPAGE   )

     I, the undersigned, a Notary Public in and for said County, in the State
aforesaid, DO HEREBY CERTIFY that Michael P. Cullinane personally known to me to
be the Exec. VP. & CFO of PLATINUM Technology, Inc. and Michael C. Wyatt
personally known to me to be the General Counsel, Secretary of said corporation,
and personally known to me to be the same persons whose names are subscribed to
the foregoing instrument, appeared before me this day in person and severally
acknowledged that as such Michael P. Cullinane CFO and Michael C. Wyatt
Secretary, they signed and delivered the said instrument as Michael P. Cullinane
CEO and Michael C. Wyatt Secretary of said corporation, and caused the corporate
seal of said corporation to be affixed thereto, pursuant to authority given by
the Board of Directors of said corporation as their free and voluntary act and
as the free and voluntary act and deed of said corporation, for the uses and
purposes therein set forth.

     GIVEN under my hand and Notarial seal this 18th day of July, 1996.

     [SEAL]                                       /s/ Maria L. Dalesandro
                                                  ---------------------------
                                                                Notary Public

STATE OF ILLINOIS  )
                   )  SS
COUNTY OF DUPAGE   )

     I, the undersigned, a Notary Public in and for said County, in the state
aforesaid, DO HEREBY CERTIFY that ________________ and ______________________,
personally known to me to be the same person(s) whose name(s) is (are)
subscribed to the foregoing instrument appeared before me this day in person and
acknowledged that _________________________ signed, sealed and delivered the
said instrument as _________________ free and voluntary act, for the uses and
purposes therein set forth, including the release and waiver of the right of
homestead.

     GIVEN under my hand and official seal this ______ day of _________________,
19_____


                                                  ______________________________
                                                                   Notary Public

                                      17
<PAGE>

                                   EXHIBIT A
                              (Plan of Premises)

     The Premises consist of that area outlined in red or a heavy line on the
plan affixed (excluding from the foregoing any, if any, elevator shafts; flues;
stacks; vertical and horizontal ducts; pillars; demising walls; electrical
boxes; firehose cabinets; and stairways) together with the right to use in
common with all other occupants of the Building, their invitees and the
Landlord, the common areas of the Building consisting of corridors, elevators
and lobby for ingress and egress to the Premises, washrooms and similar common
facilities for their intended purposes, all subject to the terms and provisions
of the Lease.

LANDLORD                                   TENANT

OAKBROOK TOWER LIMITED PARTNERSHIP         PLATINUM TECHNOLOGY, INC. a
By: M & M REALTY CORPORATION,
    GENERAL PARTNERSHIP

BY Roland V. Siegl                         BY /s/ M. Cullinane
  ---------------------------------           ----------------------------------
                                                 EXECUTIVE VICE PRESIDENT
  Its       V.P.                             Its   CHIEF FINANCIAL OFFICER
      -----------------------------             -------------------------------


ATTEST Michael Strone
      -------------------------------

  Its  Secretary
      -------------------------------

                                      A-1
<PAGE>

                       Diagram Showing Plan of Premises
<PAGE>

                                  EXHIBIT TF

                                TRADE FIXTURES

PLATINUM technology, Inc.

TRADE FIXTURES
--------------

THE FOLLOWING ARE CATEGORIES OF TRADE FIXTURES ISSUES THAT MAY BE REMOVED BY
TENANT AS TENANT'S PROPERTY, AT THE CONCLUSION OF THE LEASE TERM. BELOW EACH
GROUP ARE SOME EXAMPLES OF SPECIFIC ITEMS THAT MAY BE INCLUDED IN THE GROUP. THE
GROUP IS NOT LIMITED TO THE EXAMPLE ISSUES LISTED (A, B, C). EACH GROUP MAY
INCLUDE ADDITIONAL SIMILAR ITEMS.

1)   TELEPHONE/COMPUTER SYSTEMS:
     A)   SWITCH
     B)   PATCH PANELS
     C)   UPS SYSTEM
     D)   SUPPLEMENTAL COOLING EQUIPMENT

2)   FREESTANDING CUSTOM FURNITURE/MILLWORK:
     A)   RECEPTION DESK
     B)   CONFERENCE TABLES
     C)   APPLIANCES
     D)   PREFABRICATED COUNTER AND STORAGE UNITS
          FOR DISTRIBUTION AREAS

3)   FREESTANDING MANUFACTURED FURNITURE AND EQUIPMENT:
     A)   DESKS, CHAIRS, FILES, COUNTERS, WORKSTATIONS
     B)   COMPUTERS, PRINTERS, COPIERS

4)   ARTWORK:
     A)   PAINTINGS
     B)   GRAPHICS, MURALS
     C)   CUSTOM RUGS, UNATTACHED

5)   PLANTINGS

6)   SECURITY SYSTEMS:
     A)   CARDS, READERS
     B)   SECURITY SYSTEMS DRIVERS
     C)   CAMERAS

7)   INTERIOR SIGNAGE

8)   PAGING SYSTEMS

9)   FREESTANDING DISTRIBUTION EQUIPMENT
     A)   CONVEYOR SYSTEM
     B)   SHELVING AND PALETTE RACKS
     C)   FORK LIFTS AND CHARGING STATION
<PAGE>

                                  LEASE RIDER

          This Lease Rider is made and entered into as of the 17th day of July,
1996, at Chicago, Illinois by and between OAKBROOK TOWER LIMITED PARTNERSHIP,
not individually, but solely and only as Trustee under a certain Trust Agreement
dated the 1st day of September, 1984 and known as Trust No. 1087600 (the
"Landlord") and PLATINUM TECHNOLOGY, INC. a Delaware corporation (the
"Tenant").


                               R E C I T A L S:
                               ----------------

     A.   The Landlord and the Tenant are executing simultaneously herewith a
written lease (the "Lease") leasing certain premises (the "Premises") in the
storage area of a building (the "Building") located on the real estate commonly
known as OAKBROOK TERRACE TOWER, located at One Tower Lane, Oakbrook Terrace,
Illinois 60181, as more particularly set forth in the Lease.

     B.   The Landlord and Tenant desire to modify and amend some of the
provisions of the Lease by the terms and provisions of this lease rider (the
"Rider").

     NOW, THEREFORE, in consideration of the respective covenants of the parties
hereto contained in the Lease and in this Rider, Landlord and Tenant further
mutually agree as follows:

     1.   CONTROLLING LANGUAGE.  Insofar as the specific terms and provisions of
          --------------------
this Rider purport to amend or modify or are in conflict with the specific terms
and provisions of the Lease (the specific, but not implied), the terms and
provisions of this Rider shall govern and control; in all other respects, the
terms and provisions (and definitions) of the Lease shall remain in full force
and effect and unmodified.

     2.   BASE RENTAL TABLE.  The Tenant shall pay as Annual Base Rent and
          -----------------
monthly installment of Base Rent (pursuant to subsection 3 A of the Lease) the
following sums during the Term:

<TABLE>
<CAPTION>
================================================================================
                                           MONTHLY
     MONTHS              PER SQ/FT      INSTALLMENTS        BASE RENT
     OF TERM               RENTAL       OF BASE RENT       (ANNUALIZED)
     -------               ------       ------------       ------------
--------------------------------------------------------------------------------
<S>                      <C>            <C>                <C>
 Commencement Date -     $  7.55        $25,166.67         $302,000.00
     12/31/96
--------------------------------------------------------------------------------
 1/1/97 - 12/31/97          7.85         26,166.67          314,000.00
--------------------------------------------------------------------------------
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
==========================================================================
                                           MONTHLY
         MONTHS          PER SQ/FT       INSTALLMENTS        BASE RENT
         OF TERM          RENTAL         OF BASE RENT       (ANNUALIZED)
         -------          ------         ------------       ------------
--------------------------------------------------------------------------
<S>                      <C>             <C>                <C>
    1/1/98 - 12/31/98      8.17            27,233.33         326,800.00
--------------------------------------------------------------------------
    1/1/99 - 12/31/99      8.49            28,300.00         339,600.00
--------------------------------------------------------------------------
  1/1/2000 - 12/31/2000    8.83            29,433.33         353,200.00
--------------------------------------------------------------------------
  1/1/2001 - 12/31/2001    9.19            30,633.33         367,600.00
--------------------------------------------------------------------------
  1/1/2002 - 12/31/2002    9.55            31,833.33         382,000.00
--------------------------------------------------------------------------
  1/1/2003 - Last month
         of Term           9.94            33,133.33         397,600.00
==========================================================================
</TABLE>

          For the purposes of determining the applicable Annual Base
          Rent and monthly installments of Base Rent, the beginning
          and ending months are inclusive in the applicable rate
          periods and the first month shall be the month in which the
          Commencement Date, as determined pursuant to Section 2 of
          the Lease, occurs.

     3.   SERVICES/MAINTENANCE/REPAIRS.  Tenant shall be responsible for
          ----------------------------
obtaining and furnishing all cleaning, heating, air conditioning, ventilating,
electricity and gas to the Premises that is desired by Tenant.  Except for the
"Landlord Maintenance Items" (hereinafter defined), Tenant shall be solely
responsible at Tenant's sole cost and expense, for maintaining and repairing any
equipment necessary to furnish the above-mentioned services.  Except for the
"Landlord Maintenance Items" (hereinafter defined), and the furnishing of cold
water to the Premises, Landlord shall not be required to furnish any services to
the Premises whatsoever, including, but not limited to, janitorial services,
heating or air conditioning services, repairs or maintenance services.

          The Landlord at Landlord's sole cost and expense, does not hereby
agree to keep, maintain, repair and if necessary, replace the following items
which in the aggregate are herein referred to as the "Landlord Maintenance
Items":

               1.   The foundation and floor slabs (including the slab located
under and providing support to the loading docks) of the Building;

               2.   Any structural components of the Building including the
roof, load bearing walls and all structural walls;

               3.   Those portions and only those portions of plumbing,
electrical, utility and sewer lines which service the entire Building and are
neither owned by the applicable

                                       2
<PAGE>

utility company nor located within the Premises. Notwithstanding the foregoing,
the Tenant shall be solely responsible at Tenant's sole cost and expense for the
repair, maintenance and replacement, if necessary, of the HVAC units servicing
the Premises which are located on the roof of the Building.

          The Landlord agrees that in relation to the Landlord Maintenance Items
it shall keep the same in good condition and repair and in compliance with any
and all applicable federal, state or local laws, ordinances, rules and
regulations. The Landlord shall be responsible in relation to the Landlord
Maintenance Items for paying any and all fines or penalties assessed by any
governmental authority if said Landlord Maintenance Items fail to meet the
requirements of such applicable federal, state or local laws, ordinances, rules
and regulations. It is expressly acknowledged by Landlord and Tenant that the
Landlord Maintenance Items do not include, (i) entryways, doors, loading dock
facilities (except for the structural integrity of the slab), or rubber aprons,
doors and mechanical equipment associated with loading docks, (ii) any duty to
repair or provide any service for and in relation to utilities which are either
located within the Premises or which are owned and operated by a third party
such a public utility company, and (iii) any maintenance, repair, or replacement
of any of the Landlord Maintenance Items set forth above which is or becomes
necessary as a result of the misuse, neglect or intentional misconduct of the
Tenant.

          In the event the structural integrity of the loading dock slab shall
require repair, maintenance, or replacement the Tenant does hereby agree to
notify the Landlord of such necessity in writing. The Landlord does hereby agree
within a reasonable period of time (taking into account the time necessary to
obtain bids and award contracts), not to exceed thirty (30) days from the
receipt of Tenant's notice concerning the loading dock slab, to commence such
maintenance, repairs, or replacement, and to diligently pursue to completion
such maintenance, repair, or replacement. In the event Landlord fails to
commence or diligently pursue to completion such maintenance, repair, or
replacement, the Tenant shall have the right upon forty-eight (48) hours written
notice to the Landlord to commence or continue to completion such maintenance,
repairs, or replacement of the loading dock slab (the "Tenant Slab Self-Help
Right"). In the event the Tenant shall exercise the Tenant Slab Self-Help Right,
the Tenant shall have the right upon completion by the Tenant and/or its
contractors or agents of the repairs, maintenance, or replacement to invoice the
Landlord and the Landlord shall be required to pay within ten (10) business days
of receipt of said invoice, the reasonable costs incurred by the Tenant in so
exercising its Tenant Slab Self-Help Right, unless the Landlord shall within
said ten (10) business day time period dispute the Landlord's duty to pay for
such item based upon Landlord's belief that the Tenant was responsible for the
necessity of maintaining, repairing or replacing said loading dock slab. In the
event it becomes necessary for the Landlord and Tenant to litigate the issue of
responsibility for the payment of the cost of such repair, maintenance, or
replacement and judgement is entered in favor of the Tenant in such proceeding,
and Landlord fails to pay the Tenant such judgement within ten (10) business
days after said judgement becomes final, the Tenant shall have the right without
notice to deduct the amount of the

                                       3
<PAGE>

judgement from the next due monthly installments of Base Rent until the amount
of the judgement has been exhausted.

     4.   LANDLORD'S ACCESS TO THE PREMISES.  The Landlord does hereby agree
          ----------------------------------
that whenever the Landlord shall exercise any right of access or entry into the
Premises for purposes permitted under or pursuant to the Lease, the Landlord
shall orally notify the Tenant at least forty-eight (48) hours in advance
(except in the case of an emergency, or at any time after the Tenant is in
default of its obligations under the Lease, the applicable cure period, if any
having expired), of Landlord's intent to enter or otherwise access the Premises.
The Landlord does hereby agree that it will conduct any access or entry into the
Premises in such a manner as will cause the least interference reasonably
necessary given the nature or reason for such access or entry; provided however
that nothing herein contained shall be deemed or construed as requiring the
Landlord to conduct any right of access or entry into the Premises after hours
in the event that waiting until after hours will either exasperate an emergency
or require the Landlord to pay overtime or premium costs to contractors or
others.

          The Landlord does hereby acknowledge that the Tenant will designate
certain areas of the Premises as "Security Areas".  Notwithstanding any
provision of the Lease to the contrary, the Landlord shall not be entitled to
keys or access cards for such Security Areas.  In the event of an emergency
requiring immediate access by Landlord to such Security Areas, the Landlord
shall not be responsible to Tenant for any damage reasonably believed necessary
and caused by Landlord's accessing the Security Areas for emergency purposes.

          Notwithstanding any provision of the Lease to the contrary, the Tenant
shall be entitled to install such locks, security devices (including card key
access systems) as the Tenant desires without first notifying the Landlord in
advance. Provided, however that in relation to any such locks, security devices
(including card key access systems), the Tenant shall except in relation to
Security Areas concurrently with the installation of the same, provide the
Landlord with keys, access cards or combinations (as may be appropriate) in
relation to such newly installed items.

          Notwithstanding any provision of the Lease to the contrary, so long as
Tenant is not in default, Landlord's right to show the Premises to prospective
tenants shall be limited to the last six (6) months of the Term (as the same may
have been renewed by Landlord and Tenant). Landlord shall provide oral notice to
Tenant twelve (12) hours in advance prior to exhibiting the Premises.

     5.   SIGNAGE. Notwithstanding the provisions contained in Subsection 8F of
          --------
the Lease to the contrary, Tenant shall be entitled to paint, display, inscribe
or affix any sign, trademark, picture, advertising, notice, lettering or
direction on any part of the interior portions of the Premises without
Landlord's consent. Landlord shall not have the right to remove any of such
items except to the extent said items remain in the Premises after the
expiration of the term of this Lease.

                                       4
<PAGE>

     6.   LOAD BEARING CAPABILITIES.  The Landlord does hereby represent to the
          --------------------------
Tenant that the floor slab of the Premises is capable of bearing a load of 300
lbs. per square foot.

     7.   ADDRESS OF BUILDING.  Notwithstanding the provisions contained in
          --------------------
Section 9 of the Lease to the contrary, in the event the Landlord shall change
the street address of the Building (as opposed to said street address being
changed by the U.S. Postal service without request by the Landlord), the
Landlord agrees to provide Tenant with reasonable prior notice thereof and to
reimburse the Tenant for the reasonable costs of replacing the Tenant's
stationery, letterhead, envelopes and other similar printed documentation then
in Tenant's possession.

     8.   PRIOR OCCUPANCY.  Notwithstanding the provisions of Section 22 of the
          ----------------
Lease to the contrary, the Tenant shall have the right to access the Premises
commencing with the execution of the Lease by all necessary parties to begin the
Tenant's Work (as hereinafter defined). That period of time commencement on the
date the Lease is signed by all necessary parties and ending on the Commencement
Date is hereinafter referred to as the Prior Occupancy Period. Notwithstanding
any provision of the Lease to the contrary, the Landlord does hereby grant the
Tenant the right of limited access and limited occupancy of the Premises during
the Prior Occupancy Period without payment or accrual of liability for Rent
described in the Lease. Said right of limited access and limited occupancy shall
be solely and only for the purposes of the Tenant constructing Tenant's Work and
storing in not more than ten percent (10%) of the Premises; inventories and
supplies.

     9.   GROSS LEASE.  It is intended by the parties hereto, that with the
          ------------
exception of real estate taxes, the Lease be a Gross Lease and accordingly the
Landlord shall have no right to pass through any operating expenses relating to
the Property (except real estate taxes attributed to the warehouse/storage
portion of the Property as hereinafter described) directly to the Tenant as is
the case with office tenants of the Property.  It expressly acknowledged by the
Tenant however, that the Tenant is responsible for certain other costs which, if
not paid by the Tenant shall constitute an additional component of Rent under
specific provisions of the Lease.  Such additional costs include the costs
associated with or resulting from the necessity to repair and/or maintain the
Premises due to Tenant's failure to perform its maintenance and repair
obligation under the Lease as amended, the costs of remedying any default of the
Tenant, the payment of bills for water or other services provided by Landlored
or other third parties (including the municipality) and for Tenant's
indemnification duties hereunder.

     10.  REAL ESTATE RENT.  In addition to every other component of Rent
          -----------------
specified in the Lease and this Rider the Tenant shall pay to the Landlord
50% of the real estate taxes attributable to the warehouse/storage portion of
the Property (the "Tax Rent").  The Tenant shall be required to pay to the
Landlord estimated deposits of the Tax Rent (the "Tax Rent Deposits") on the
first day of each and every month of the Term.  The Tax Rent Deposits shall be
equal to one twelveth (1/12) of Landlord's reasonable estimate of Tax Rent as
communicated in writing by the Landlord to the Tenant.  The Landlord reserves
the right to adjust the Tax Rent

                                       5
<PAGE>

Deposits from time to time upon not less than thirty (30) days prior written
notice.  Within a reasonable time after Landlord's receipt of the tax bill
applicable to the storage/warehouse portion of the property on which the
Building is located for the applicable year of the Term for which the Tax Rent
is being calculated (the"Calculation Year"), the Landlord shall cause to be
furnished to Tenant a statement showing the following:

          (i)   Real estate taxes attributable to the warehouse/storage portion
of the Property for the Calculation Year as indicated on the real estate tax
bills for pin number 06-23-101-023;

          (ii)  The amount of the Tax Rent due to the Landlord for the
Calculation Year less credit for the Tax Rent Deposits paid by the Tenant in and
allocable to said Calculation Year; and

          (iii) The Tax Rent Deposits due monthly as aforesaid during the
calendar year next following the Calculation Year for which such statement is
given (subject to revision as aforesaid) including the amount or revised
amount for the months prior to the rendition of the statement.

          Within thirty (30) days after receipt of such statement the Tenant
shall pay to the Rental Agent the amount of the Tax Rent due to the Landlord for
the Calculation Year as reflected in said statement and the amount of the Tax
Rent Deposits due for the months between the expiration of the Calculation Year
described in the statement to and including the month in which the statement is
furnished. If such statement reflects an amount due from the Landlord to the
Tenant the Landlord shall apply such amount against the next due Tax Rent
Deposits until exhausted and refunds to the Tenant any remaining unapplied
amount at the end of the Term.

          If the Lease Term commences on any day other than the first (1st) day
of January or if the Lease Term ends on any day other than the last day of
December, any Tax Rent payment due Landlord shall be prorated and the Tenant
shall pay such amount within ten (10) days after being billed. Tenant's
obligation and covenant to pay the Tax Rent Deposits and the Tax Rent are each
and all independent of every other covenant set forth in the Lease and shall
survive the expiration or termination of the Lease.

     Landlord and Tenant do hereby acknowledge that the Tax Rent shall consist
solely and only of the general real estate taxes attributable to the storage
warehouse portion of the Property on which the Building is located, and any
special assessments of taxes levied on such storage warehouse portion of the
Property on which the Building is located. The Landlord and Tenant do hereby
agree that in regard to any special assessment which may be paid in installments
whether or not the Landlord elects to pay such special assessment in
installment, the Tenant shall only be responsible for the portions of such
special assessment which would become due and payable during the Term had the
Landlord elected to pay the same in installments.

                                       6















<PAGE>

     11.  LANDLORD'S WORK. The Landlord does hereby agree to cause the following
          ---------------
alterations, improvements, and repairs (in the aggregate "Landlord's Work") to
be accomplished on the Premises and Property at Landlord's sole cost and
expense:

          1.   Re-roof the entire warehouse building utilizing a roofing
               contractor mutually acceptable to Landlord and Tenant;

          2.   In conjunction with the re-roofing referred to above, remove the
               HVAC unit located at the southwest corner of the roof;

          3.   Clean concrete floor within the Premises and grind down existing
               exposed bolts in said floor;

          4.   Install power supply to adapt to Tenant's reasonable alarm
               requirements in conjunction with Tenant's contractor; and

          5.   Disconnect and remove abandoned telephone wires.

          The Landlord agrees to commence the Landlord's Work within a
reasonable period of time after receiving the Tenant's Plans (as hereinafter
defined) and to complete the same within a reasonable period of time given the
type and progress of the Tenant's Work. The Landlord and Tenant agree to
reasonably cooperate in scheduling Landlord's Work and Tenant's Work so that
they do not unreasonably interfere with each other's work or unreasonably delay
the completion of the either the Landlord's Work or the Tenant's Work. It is
expressly acknowledged by the Landlord and the Tenant that no delay in
completion of the either the Landlord's Work or Tenant's Work shall delay the
commencement of the Term or the Tenant's duty to pay all components of Rent
under the Lease which shall begin irrespective of the completion or
non-completion of Landlord's or Tenant's Work on the Commencement Date.

          In the event item numbers 1 and 2 above of the Landlord's Work are not
completed by August 31, 1996 and the non-completion of the said items 1 and 2 of
Landlord's Work has resulted from the failure of the Landlord to award contracts
for said items 1 and 2 of the Landlord's Work or the failure of the Landlord to
replace contractors to whom awards of said items 1 and 2 of Landlord's Work have
been made but who have failed to diligently pursue completion of said items 1
and 2 of Landlord's Work, the Tenant shall have the right upon forty-eight (48)
hours prior written notice to the Landlord to hire a contractor reasonably
acceptable to Landlord to complete items 1 and 2 of Landlord's Work (the
"Landlord's Work Self-Help Right"). In the event the Tenant shall exercise its
Landlord's Work Self-Help Right, the Landlord shall, pay to the Tenant the
reasonable costs incurred by the Tenant in exercising its Landlord's Work
Self-Help Right within ten (10) business days of receiving invoices and proof of
payment relating to the same. In the event the Landlord shall fail to pay the
Tenant such reasonable costs within said ten (10) business day time period, the
Tenant shall have the right without notice to deduct such reasonable costs from
the next due monthly installments of Base

                                       7
<PAGE>

Rent until exhausted. The Tenant and Landlord do hereby acknowledge that the
Tenant shall not have the right to exercise the Landlord's Work Self Help Right
as to any items of Landlord's Work other than the items 1 and 2 above.
Furthermore, the Tenant shall have no right to exercise the Landlord's Work Self
Help Right in the event that items 1 and 2 above of Landlord's Work are not
completed by August 31, 1996 as a result of a delay caused by the Tenant,
scheduling conflicts with the "General Contractor" (as defined in Section 14
hereof), or delays due to acts of God, strikes, governmental control or other
factors beyond the reasonable control of the Landlord.

     12.  HEALTH CLUB MEMBERSHIPS. The Tenant is hereby granted two (2) health
          -----------------------
club memberships in the health club located in the Building, free from initial
membership initiation fees. Tenant shall be responsible for the payment of all
other dues and/or fees imposed by the health club operator, including but not
limited to monthly dues, guest fees, and membership renewal and transfer fees
associated with such memberships. Tenant must complete and submit to the health
club operator a membership application designating an officer or employee of
Tenant thereon for such membership. Such membership is for the use and only for
the use of the officer or employee of Tenant whose name is contained on the
membership application approved by the health club operator and, subject to
payment of guest fees, the invitees of such member. The Tenant shall be required
in utilizing such membership to comply with all reasonable rules and regulations
promulgated by the health club operator in association with such use of health
club facilities.

     13.  RENEWAL OPTION. The Tenant is  hereby granted one (1) five (5) year
          ---------------
option to renew the Lease (the "Renewal Option") at a Base Rental Rate equal to
95% of the then "current building market rate", for similar upper level storage
space (and office use ancillary thereto) as reasonably determined by the
Landlord taking into account the rate (excluding market concessions) at which
similar space in the Building and other Class A Buildings within a five (5) mile
radius of the Building are then being offered (the "Extended Term Rent"). If the
Tenant desires to exercise its Renewal Option, it shall do so in the following,
and only in the following, manner:

               A.   If the Tenant desires to exercise its Renewal Option, it
shall so notify the Landlord, in writing, no earlier than the first day of the
12th month prior to the then current expiration date of the Lease Term and no
later than the first day of the sixth (6th) month prior to the then current
expiration date of the Lease Term. Such notice shall only be effective if
delivered at a time when the Tenant is not in default of its obligations beyond
any, if any applicable notice and cure periods, under the terms and provisions
of the Lease and this Rider.

               B.   Within a reasonable period of time after receipt of Tenant's
notice of its desire to exercise its Renewal Option, given at the time and in
the manner provided above, the Landlord shall prepare and transmit to the Tenant
an appropriate lease amendment to the Lease extending the Term for five years
(the "Extended Term") and modifying the Base Rent to equal the Extended Term
Rent, modifying the monthly installments of the Base Rent to equal

                                       8
<PAGE>

1/12th of the new Base Rent, as determined aforesaid and including all market
concessions utilized to determine the Extended Term Rent.

               C.   The Landlord shall transmit such lease amendment to the
Tenant for execution and Tenant shall execute and deliver the same to the
Landlord within ten (10) business days of Tenant's receipt thereof. In the event
the Tenant fails for any reason to execute and deliver the lease amendment to
the Landlord within the time period provided herein, then in such event, at
Landlord's option and only at Landlord's option, Tenant's purported exercise of
its Renewal Option shall be of no force or effect and the Renewal Option shall
become null and void.

               D.   Sections 2, 8, 11, 14, and 15 of this Rider shall be of no
force or effect during such Extended Term brought about as a result of Tenant's
exercise of its Renewal Option.

               E.   Notwithstanding any of the foregoing, if Tenant disputes
Landlord's determination of the rental rate for the Extended Term, then Tenant
shall provide notice of such dispute within fifteen (15) days following
Landlord's delivery of the amendment referred to above. In the event Landlord
and Tenant are unable to agree on the Extended Term Rent within fifteen business
days following Tenant's delivery of notice of such dispute to Landlord, then
either Tenant or Landlord shall be entitled to terminate the exercise of the
Renewal Option and such Renewal Option shall be deemed null and void.

     14.  TENANT'S CONSTRUCTION AND ALTERATION. Notwithstanding any provision of
          ------------------------------------
the Lease to the contrary, included but not limited to the provisions contained
in Subsection 8Q thereof, the Landlord and Tenant do hereby acknowledge that the
Tenant desires to make certain improvements and alterations in and to the
Premises and to commence making those improvements and alterations prior to
occupying the Premises for business purposes therein and may desire to continue
to make alterations or improvements to the Premises until December 31, 1996 (in
the aggregate those improvements and alterations desired by the Tenant prior to
December 31, 1996 are hereinafter referred to as the "Tenant's Work"). In
relation to any Tenant's Work, the Tenant shall be required to prepare and
submit to Landlord at Tenant's sole cost and expense all plans, specifications,
information and architectural, engineering and mechanical drawings concerning
Tenant's Work (in the aggregate the "Tenant's Plans"). The Landlord shall review
Tenant's Plans and either approve the same or disapprove the same, giving
specific reasons for said disapproval, within a reasonable period of time after
Landlord's receipt of Tenant's Plans. In the event the Landlord disapproves of
the Tenant's Plans the Tenant may revise the Tenant's Plans in accordance with
the comments contained in Landlord's notice of disapproval and resubmit Tenant's
Plans as modified to Landlord for review and approval. The Landlord does hereby
agree to not unreasonably withhold or delay its approval to Tenant's Plans (as
the same may be modified).

                                       9
<PAGE>

     Once Tenant's Plans have been approved by the Landlord, the Tenant shall
use Leopardo Construction Company as the general contractor (the "General
Contractor"). The General Contractor shall carry adequate insurance, insuring
both the Landlord and Tenant, supply general contractor statements, appropriate
partial and final lien waivers and certifications and/or guarantees concerning
the work performed by the General Contractor. The Tenant shall enter into the
written contract with the General Contractor for the Tenant's Work and shall be
responsible for all costs associated therewith. The Tenant does hereby agree to
indemnify, defend and hold the Landlord harmless from and against any and all
claims of the General Contractor or arising out of the Tenant's Work. The Tenant
does hereby further agree to provide to the Landlord such reasonable proof as
Landlord may reasonably request concerning the status of Tenant's Work, payments
therefore, and the completion of the Tenant's Work in compliance with all
applicable laws, rules and regulations.

     It is expressly acknowledged by Tenant that the Landlord shall have no
responsibility regarding the quality of the Tenant's Work nor its usefulness for
the purposes desired by the Tenant or for any delays of the General Contractor.

     15.  ALTERATION ALLOWANCE. The cost of all Tenant's Work to be performed in
          --------------------
or to the Premises shall, subject to the allowance hereinafter granted by the
Landlord, be the sole responsibility of the Tenant. The Landlord does hereby
grant to the Tenant an allowance equal to $400,000.00 (the "Alteration
Allowance"). The Landlord agrees to pay the Tenant the Alteration Allowance as
the Tenant's Work progresses (but in no more than four (4) draws). Within thirty
(30) days of receipt from the Tenant of; (a) sworn contractors statements; (b)
partial and/or final lien waivers, as the case may be; (c) certification by the
Tenant that it is satisfied with the work to date; and (d) proof by the Tenant
that it has paid the General Contractor the amounts specified in the Tenant's
draw request. Notwithstanding the foregoing the Landlord shall not be required
to pay the Tenant any portion of the Alteration Allowance while any pending lien
is outstanding for and in relation to the Tenant's Work unless Tenant bonds over
the same to the satisfaction of Landlord's title insurance carrier, nor shall
the Landlord be required to pay more than 80% of the Alteration Allowance until
such time as all of the Tenant's Work has been completed and the Tenant has
provided the reasonable proof specified above for and in relation to said final
completion of the Tenant's Work. It is expressly acknowledged by Landlord and
Tenant that the Alteration Allowance described in this Section 11 shall apply
solely and only to the Tenant's Work desired by the Tenant in and to the
Premises and completed prior to December 31, 1996. Any unused portion of the
Alteration Allowance as of January 1, 1997 shall be applied by the Landlord
until exhausted, against the Tenant's duty to pay monthly installments of Base
Rent.

     16.  PROHIBITED USES. Notwithstanding the provisions of Section 6 and
          ---------------
Subsection 8 J of the Lease to the contrary; (i) the Tenant is hereby granted
the right to bring food into the Premises for preparation and consumption by
Tenant's employees and business invitees only; (ii) the Landlord agrees that it
will not unreasonably withhold its consent to the installation by Tenant of
refrigerators, microwave ovens or coffee warmers in the Premises for

                                      10
<PAGE>

the sole use of Tenant's employees and business invitees; (iii) the Tenant shall
be permitted to install and operate heating and air conditioning apparatus
within the Premises; and (iv) the Tenant shall be permitted as ancillary use
(and not as a primary use) to utilize not more than thirty three percent (33%)
of the Premises for office purposes.

     17.  MUTUAL INCORPORATION. All negotiations, considerations,
          --------------------
representations and understandings between Landlord and Tenant are incorporated
herein and may be modified or altered only by agreement, in writing, between
Landlord and Tenant. No modifications, termination, or surrender of the Lease or
surrender of the Premises or any part thereof or of any interest therein by
Tenant shall be valid or effective unless agreed to and accepted, in writing, by
the Landlord and no act by any representative or agent of the Landlord other
than delivery of such a written agreement and acceptance by the Landlord shall
constitute acceptance thereof. Any prior negotiations or intentions of the
parties, whether oral or evidenced by written documentation dated prior to the
date of this Lease, are null and void.

     18.  REMOVAL OF ADDITIONS. Notwithstanding the provisions contained in
          --------------------
Section 15 of the Lease, Tenant shall be entitled to remove any of the
installations, additions, hardware, non-trade fixture and improvements set forth
in Exhibit TF to this Lease.

          Notwithstanding any provision of subsection 15 C of the Lease to the
contrary, the Tenant, upon termination of the Lease, shall not be required to
remove any installations, additions, hardware, non-trade fixtures and
improvements, temporary or permanent (except movable furniture, trade fixtures
and equipment belonging to the Tenant and the items specified on Exhibit TF)
initially installed in the Premises, unless the Landlord shall have stated in
writing such specific items for removal at the expiration of the Term at the
time of Landlord's approval of Tenant's Plans. The Tenant shall have the right
from time to time during the Term to inform the Landlord by written notice of
any new installations, additions, hardware, non-trade fixtures and improvements,
temporary or permanent, which Tenant intends to bring into or incorporate into
the Premises and receive a designation from Landlord pursuant to said subsection
15 C of the Lease as to whether or not the Landlord will require the Tenant to
remove such item at the expiration of the Term. If Landlord does not respond to
the Tenant's notice within ten (10) business days of Landlord's receipt of
Tenant's notice, the Tenant will not be required to remove any of the items
identified by Tenant in its notice at the expiration of the Term. Landlord's
waiver of its rights under said subsection 15 C of the Lease, as set forth
herein, shall only apply to items originally incorporated in the Premises and
indicated on the Tenant's Plans or subsequent requests from the Tenant as being
exceptions to the removal rights of Landlord pursuant to said subsection 15 C of
the Lease and consented to by Landlord.

     19.  WAIVER AND INDEMNITY.
          --------------------

               A.   (1)  To the extent permitted by law, Tenant releases
Landlord Related Parties (as defined in Section 19) from, and waives all claims
for, damage to person or property sustained by Tenant or any occupant of the
Premises or Property resulting from the

                                      11
<PAGE>

Property or Premises or any part of either or any equipment or appurtenance
becoming out of repair or resulting from any accident in or about the Property,
or resulting directly or indirectly from any act or omission of any tenant or
occupant of the Property or of any other person, other than Landlord Related
Parties. This Section 19 shall apply especially, but not exclusively, to the
flooding of basements or other subsurface areas, and to damage caused by
refrigerators, sprinkling devices, air conditioning apparatus, water, snow,
frost, steam, excessive heat or cold, falling plaster, broken glass, sewage,
gas, odors or noise, or the bursting or leaking of pipes or plumbing fixtures
and shall apply equally whether such damage be caused or result from anything
or circumstance above mentioned or referred to, or any other thing or
circumstance whether of a like nature or of a wholly different nature.

               (2)  The Landlord Related Parties shall not be liable for any
loss or damage to property even if due to the negligence, gross negligence or
intentional misconduct of any of the Landlord Related Parties, to the extent of
the greater of: (i) the recovery by Tenant under any property damage insurance
carried by it (whether or not required to be carried by the terms of the Lease);
or (ii) such amounts as would have been recovered if Tenant had carried the
insurance required under the Lease. Tenant shall make reasonably diligent
efforts to recover from its insurers the full amount of any insured claim.

          B.   (1)  To the extent permitted by law, Landlord releases Tenant
Related Parties (as defined in Section 19) from, and waives all claims for,
damage to person or property sustained by Landlord or any occupant of the
Premises or Property resulting from the Property or Premises or any part of
either or any equipment or appurtenance becoming out of repair or resulting from
any accident in or about the Property, or resulting directly or indirectly from
any act or omission of any tenant or occupant of the Property, or of any other
person, other than Tenant Related Parties. This Section 19 shall apply
especially, but not exclusively, to the flooding of basements or other
subsurface areas, and to damage caused by refrigerators, sprinkling devices, air
conditioning apparatus, water, snow, frost, steam, excessive heat or cold,
falling plaster, broken glass, sewage, gas odors or noise, or the bursting or
leaking of pipes or plumbing fixtures and shall apply equally whether such
damage be caused or result from any thing or circumstance above mentioned or
referred to, or any other thing or circumstance whether of a like nature or of a
wholly different nature.

               (2)  The Tenant Related Parties shall not be liable to Landlord
for any loss or damage to property even if due to the negligence, gross
negligence or intentional misconduct of any of the Tenant Related Parties to the
extent of the greater of: (i) the recovery of Landlord under any property damage
or rent loss insurance carried by it (whether or not required to be carried by
the terms of the Lease); or (ii) such amount as would have been recovered if
Landlord had carried the insurance required under the Lease. Landlord shall make
reasonably diligent efforts to recover from its insurers the full amount of any
insured claim.

          C.   Except as provided in Section 19 or as specifically set forth in
the Lease, Tenant agrees to indemnify and save all of the Landlord Related
Parties harmless against any

                                      12
<PAGE>

and all claims, demands, liabilities, costs and expenses, including, without
limitation, reasonable attorneys' fees for the defense thereof, arising from any
breach or default on the part of Tenant in the performance of any covenant or
agreement on the part of Tenant to be performed pursuant to the terms of this
Lease, or from any negligence of any of the Tenant Related Parties in or about
the Property or Premises. In case of any action or proceeding brought against
any of the Landlord Related Parties by reason of any such claim, upon notice
form Landlord, Tenant covenants to defend such action or proceeding by counsel
reasonably satisfactory to Landlord. Except as provided in Section 19 or as
specifically set forth in the Lease, Landlord agrees to indemnify and save all
of the Tenant Related Parties harmless against any and all claims, demands,
liabilities, costs and expenses, including, without limitation, reasonable
attorneys' fees for the defense thereof, arising from any breach or default
on the part of Landlord in the performance of any covenant or agreement on the
part of Landlord to be performed pursuant to the terms of this Lease, or from
any negligence of any of the Landlord Related Parties in or about the Property
of Premises. In case of any action or proceeding brought against any of the
Tenant Related Parties by reason of any such claim, upon notice from Tenant,
Landlord covenants to defend such action or proceeding by counsel reasonably
satisfactory to Tenant.

          D.   For purposes of this Section 19:

               (1)  "Landlord Related Parties" means Landlord, Miglin-Beitler
Management Corporation, the beneficiaries of Landlord, the partners which
comprise the beneficiaries of Landlord, the partners which comprise such
partners, and the agents, employees, officers, directors, shareholders, partners
or principals (disclosed or undisclosed) of any of them.

               (2)  "Tenant Related Parties" means Tenant and the officers,
directors, agents and employees of Tenant (whether disclosed or undisclosed).

          20.  ASSIGNMENT AND SUBLETTING. Notwithstanding the provisions
               -------------------------
contained in Section 16 of the Lease, without Landlord's consent and without
being subject to; (i) Landlord's right to recapture; or (ii) any obligation to
share excess rent, Tenant shall have the right, so long as it is not in default
beyond any, if any applicable nature and cure period, to assign or sublease all
or a portion of the Premises to:

               (a)  any entity succeeding to the business and assets of Tenant
                    except by way of bankruptcy or consolidation in lieu of
                    bankruptcy; and

               (b)  any entity which is a subsidiary or an affiliate of Tenant.

               Tenant shall, however, prior to the effective date of such
assignment or sublease, cure any defaults of the Tenant and notify Landlord in
writing of its intent to so assign or sublease, and the portion of the Premises
to which such sublease or assignment pertains, and the resulting entity that
will be the Tenant hereunder.

                                      13
<PAGE>

               In addition to the above, Tenant shall have the right, without
Landlord's consent, to assign this Lease to any entity which controls, is
controlled by, or is under common control with Tenant, or any entity resulting
from a merger or consolidation with Tenant, or which acquires all or
substantially all Tenant's assets, provided, however, that the foregoing are not
as a result of bankruptcy or reorganization in lieu thereof. Nothing herein
contained shall be deemed or construed as relieving Tenant from any liability
under the terms and provisions of the Lease as a result of any assignment or
sublet pursuant to the aforesaid.

               Notwithstanding any provision of Section 16 of the Lease to the
contrary, in the event the Tenant shall make an assignment of the Lease to any
entity, which pursuant to the provisions above in this Section 20 does not
require the Landlord's consent, such entity shall have the rights (if any)
contained in the Lease as amended, to (i) extend or renew the term; (ii) lease
additional space in the Building; (iii) utilize reserved underground parking
spaces; and (iv) utilize health club memberships. Nothing herein contained shall
be deemed or construed as requiring the Landlord to offer to such assignee the
aforementioned rights, unless, and then only to the extent such rights have been
specifically granted to the Tenant pursuant to the terms and provisions of the
Lease.

     21.  CONDEMNATION. Notwithstanding the provisions contained in Section 19
          ------------
of the Lease, the Tenant shall be entitled to seek a condemnation award relating
to moving expenses, loss of Tenant's property and the unamortized value of
Tenant's leasehold improvements within the Premises paid for by Tenant without
reimbursement or credit from Landlord, notwithstanding that such award may undue
any award inuring to the benefit of Landlord. Any condemnation which takes all
or a substantial part of the Loading Dock or materially limits the Tenant's
ability to access the Loading Dock, shall be treated as a condemnation of the
entire Premises.

     22.  INSURANCE. At all times during the term of this Lease, Landlord shall
          ---------
at its sole cost and expense maintain in full force and effect insurance
protecting Landlord and Tenant and their respective agents and any other parties
designated by Tenant from time to time, with terms, coverages and at companies
reasonably satisfactory to Tenant. Such coverage shall be in the following
amounts:

     (i)   Comprehensive General Liability Insurance, including contractual
           liability insuring the indemnification provisions contained in this
           Lease, with limits of not less than Two Million Dollars ($2,000,000)
           combined single limit per occurrence for bodily injury, death and
           property damage. The Comprehensive General Liability policy shall
           include as additional insureds the Tenant and its agents, with a
           severability of interest endorsement.

     (ii)  Insurance against all risks of physical loss coverage, moveable
           fixtures, office equipment, furniture, trade fixtures, merchandise
           and all other improvements and betterments constituting the Premises,
           Building and/or Property.

                                      14
<PAGE>

     Landlord shall, prior to the commencement of the term hereof and prior to
the expiration of any policy, furnish Tenant certificates evidencing that all
required insurance is in force and providing that such insurance shall not be
canceled or changed without at least thirty (30) days' prior written notice to
Tenant (unless such cancellation is due to nonpayment of premiums, in which
event ten (10) days' prior written notice shall be provided).

     23.  BROKERS. Landlord hereby warrants and represents that it has not
          -------
employed or dealt with any other broker or finder in connection with this Lease
of the Premises except Stein & Company and Miglin-Beitler Management
Corporation. Landlord further covenants and agrees that it shall be responsible
to pay any and all commission to Stein & Company and Miglin-Beitler Management
Corporation in connection with this Lease. Landlord shall indemnify, defend,
protect and hold Tenant harmless from and against any claims, losses,
liabilities, demands, costs, expenses or causes of action by any other broker,
agent or person claiming a commission or other form of compensation by virtue of
having represented Landlord with regard to this Lease and transaction.

     24.  RULES AND REGULATIONS. Notwithstanding any provision of the Lease to
          ---------------------
the contrary, the Landlord does hereby acknowledge that it does not have
standardized rules for the office warehouse Building. The Landlord reserves the
right at any time during the Term to promulgate reasonable rules and regulations
for the office warehouse Building for the protection and welfare of the Building
and property and its tenants and occupants. The Landlord does hereby agree that
any such rules and regulations shall not materially impair the Tenant's use and
occupancy of the Premises, or its access rights and use of the loading dock
servicing the Premises. The Landlord does hereby agree that any such rules and
regulations shall be non-discriminatory in nature and shall be uniformly applied
to all tenants of the Building. Nothing herein contained shall be deemed or
construed as relieving the Tenant of compliance with all laws, ordinances,
orders, and regulations and with the directions of any public officer authorized
by law with respect to the Premises and the use and occupancy thereof by Tenant.

     25.  HAZARDOUS MATERIALS.  Notwithstanding the provisions contained in
          -------------------
Subsection 8I of the Lease, the Tenant shall be permitted to bring into and keep
in the Premises such hazardous materials as are normally and customarily
utilized in a storage warehouse/office environment, including, but not limited
to, cleaning materials and photostatic chemicals. The Tenant shall be
responsible for compliance with all laws, ordinances, rules and regulations
promulgated by any governmental authority having jurisdiction over the Property
and/or the Premises in relation to the use or presence of such hazardous
materials. Tenant does hereby agree to indemnify and save the Landlord harmless
from and against any and all claims, costs and expenses (including reasonable
attorney's fees), incurred by the Landlord resulting from or arising out of the
presence, use, or maintenance on the Premises and within the Property of
hazardous materials brought on to the Property by the Tenant, its employees,
agents, contractors, and invitees. Notwithstanding any provision of the Lease to
the contrary, the Landlord does hereby agree to indemnify and defend and hold
the Tenant harmless from and against any and all claims, costs and expenses
(including reasonable attorney's fees), resulting

                                      15
<PAGE>

from the presence of hazardous material in the Premises or on the Property which
have been brought thereon by Landlord, its employees, agents, contractors, and
invitees; provided however that for the purposes hereof, other tenants on the
Property as well as their respective employees, agents and invitees shall not,
for the purposes hereof be deemed agents or invitees of the Landlord.

     26.  ABANDONMENT.  Notwithstanding any provision of the Lease to the
          ------------
contrary, the Tenant shall not be deemed or construed to have abandon the
Premises unless the Tenant has vacated the Premises and is not current in its
obligations to pay Rent.

     27.  TENANT'S ACCESS AND USE RIGHTS.  Notwithstanding the provisions
          -------------------------------
contained in Subsection 9H of the Lease, the Landlord does hereby acknowledge
that the Tenant will be conducting 24-hour operations from the Premises. Tenant
shall be entitled to have access to the Premises and arrange for delivery and
shipping of its inventory and items stored therin (subject to necessary
maintenance and repair and the laws, ordinances, rules and regulations
promulgated by any governmental authority having authority over the Premises and
the Property) on a 24-hour basis, seven (7) days per week through the loading
dock area for the Premises. The Tenant hereby acknowledges that Landlord may
impose reasonable restrictions on Tenant or its employees, agents, contractors,
or invites from entering the other building (the "Office Building") located on
the Property, and from main areas of the Building during non-business hours.

     28.  RESTORATION/CANCELLATION.  Notwithstanding the provisions of Section
          -------------------------
17 of the Lease, in the event the Premises are made partially or wholly
untenantable by fire or other casualty and the Landlord elects to rebuild,
restore or repair the Building or the Premises but fails to complete such
rebuilding, repairing or restoring within 180 days after such fire or other
casualty, and subject to the provisions of Section 26 A of the Lease (but in no
event more than 240 days after the date of such fire or casualty), the Tenant
shall have the right, upon written notice delivered prior to the Premises being
restored, to cancel the Lease as of the date of such fire or other casualty.

     29.  NON-MONETARY DEFAULTS.  Notwithstanding the provisions of subsection
          ---------------------
18B of the Lease to the contrary, in the event a non-monetary default to which
the ten (10) day time period set forth in said Subsection 18B is not cured by
the Tenant within said ten (10) day time period, but the Tenant commences to
cure such default within said ten (10) day time period and diligently pursues a
cure of such non-monetary default and the same is capable of being cured, such
ten (10) day cure period for non-monetary defaults shall be extended for so long
as the Tenant is actively and diligently attempting to effectuate a cure of such
non-monetary default.

     30.  COST OF ENFORCEMENT.  The Landlord shall pay all Tenant's costs,
          --------------------
charges and expenses, including the fees of counsel, agents and other retained
by Tenant, incurred in enforcing Landlord's obligations hereunder or incurred
by Tenant in any litigation,

                                      16
<PAGE>

negotiation, or transaction in which Landlord causes Tenant, without Tenant's
fault, to become involved or concerned.

     31.  NON-DISTURBANCE AGREEMENT.  Notwithstanding the provisions of Section
          --------------------------
20 of the Lease to the contrary, the Tenant shall not be deemed to have
subordinated its interest under this Lease to any mortgage or trust deed or
ground lease that now exists or may hereinafter be placed upon the Building,
Real Estate, or Property unless such mortgagee, trustee or groundlessor shall
have provided the Tenant with a standard form of non-disturbance, attornment and
recognition agreement substantially in the form attached to the Lease as Exhibit
G. Landlord agrees to obtain such non-disturbance and attornment agreement from
any existing mortgagee, trustee or groundlessor as soon as feasible.

     32.  MISCELLANEOUS.  Notwithstanding anything to the contrary contained in
          --------------
this Lease, Landlord hereby represents, covenants, warrants and agrees that (i)
Landlord has complete and lawful title (subject to a mortgage) to the building
and has full right, power and authority to enter into and execute and deliver
this Lease; (ii) as of the date hereof to the best of Landlord's knowledge
without making inquiry, the Building and Property comply with all applicable
laws, ordinances, regulations and requirements of governmental authorities
having jurisdiction thereof; (iii) it has not received nor has any notice of any
building, municipal or health department code, regulation, statue or law which
would adversely affect Tenant's leasehold improvement in the Premises and/or
Tenant's operation of its business in the Premises; (iv) it has no knowledge of
any existing or pending special assessment applicable to the Property; and (v)
the real Estate tax PIN number specified in Subparagraph 10(i) above concerns
the storage/warehouse portion of the Property and does not include the highrise
office portion of the Property.

     33.  HVAC CREDIT.  The Tenant is hereby granted a credit (the "HVAC
          ------------
Credit") equal to the lessor of, (i) the actual costs incurred by the Tenant in
installing two (2) condenser units and two (2) gas furnaces in the Premises (or
in the case of the condenser units on the roof of the Building), or (ii)
$8,755.00. The Landlord agrees to pay the Tenant the HVAC Credit within thirty
(30) days of the Landlord's receipt of paid invoices evidencing the actual cost
incurred by the Tenant relating to said two (2) condenser units and two (2) gas
furnaces. The Landlord and Tenant do hereby acknowledge that this HVAC Credit
has been granted in exchange for a modification of the Landlord's obligation
concerning the air conditioning unit located on the southwest corner of the roof
of the Building, In relation to said air conditioning unit located on the
southwest corner of the roof of the Building, the Landlord's only obligation
shall be to remove the same as provided above in this Rider.

     34.  PRE-COMMENCEMENT DATE STORAGE.  Notwithstanding the provisions
          ------------------------------
contained in Subsection 2(iii) of the Lease, the utilization by the Tenant of
not more than ten percent (10%) of the area of the Premises for storage prior to
October 15, 1996 shall not in and of itself trigger the occurrence of the
"Commencement Date".

                                      17
<PAGE>

     35.  LANDLORD'S SUPERVISION FEES. The Landlord does hereby agree that any
          ---------------------------
and all supervision fees for and in relation to alterations desired by the
Tenant and conducted pursuant to Subsection 8Q of the Lease shall be limited
solely and only to the direct costs actually incurred by Landlord in so
supervising any such alterations.

     36.  SCAVENGER SERVICE. The Tenant shall make its own arrangements and be
          -----------------
responsible for all costs incurred for waste and garbage disposal and pick-up
from the Premises.

     37.  LANDLORD'S EXCULPATION. Landlord's exculpation clause, as set forth in
          ----------------------
Section 28 of the Lease, is incorporated herein by reference, as if full set
forth.

     IN WITNESS WHEREOF, this instrument has been duly executed by the parties
hereto, as of the date first above written.

LANDLORD                               TENANT
--------                               ------
OAKBROOK TOWER LIMITED PARTNERSHIP     PLATINUM TECHNOLOGY, INC. a
By: M&M REALTY CORPORATION,            Delaware corporation
    GENERAL PARTNER

BY: Roland V. Siegl                     BY: /s/ M. Cullinane
   -------------------------------        --------------------------------------
      Its    V.P.                            Its Executive Vice President
         -------------------------               Chief Financial Officer
                                                --------------------------------

Attest: Michael Strone                   Attest   /s/ Michael C. Wyatt
       ---------------------------            ----------------------------------
                                                      Michael c. Wyatt

                                                Its  Vice President and General
                Secretary                               Counsel
         Its _____________________                   ---------------------------

                                      18
<PAGE>

STATE OF   Illinois      )
        ----------------
                         ) ss
COUNTY OF DuPage         )
          --------------


     I, Maria L Dalesandro, a Notary Public in and for said County, in the State
aforesaid, DO HEREBY CERTIFY that Michael P. Cullinane, personally known to me
to be the CFO of PLATINUM TECHNOLOGY, INC. a Delaware corporation authorized to
conduct business in the State of Illinois, and Michael C. Wyatt, personally
known to me to be the General Counsel, Secretary of said corporation, and
personally know to me to be the same persons whose names are subscribed to the
foregoing instrument, appeared before me this day in person and severally
acknowledged that as such CFO and ______________ Secretary, they signed and
delivered the said instrument as ______________ President and ____________
Secretary of said corporation, and caused the corporate seal of said corporation
to be affixed thereto, pursuant to authority given by the Board of Directors of
said corporation as their free and voluntary act for the uses and purposes
therein set forth.

     GIVEN under my hand and NOTARY seal this 18th day of July, 1996.



     [SEAL]                                       /s/ Maria L. Dalesandro
                                                  -----------------------
                                                       Notary Public

                                      19
<PAGE>

<TABLE>
<CAPTION>
PLATINUM - LEASE ABSTRACT
------------------------------------------------------------------------------------------------------------------------------------
<S>                                <C>                          <C>                                <C>
Lease ID/Site ID                   38/31                        Expiration Notice Comments

Old Lease ID                                                    Renew Notice                       04/14/2002
Last Update                        01/08/1997                   Renewal Notice Comments            One five year option at 95%
                                                                                                   of market. See lease rider,
                                                                                                   item 13.
RSF                                40,000
Suite/Floor
Building Name                      Oakbrook Terrace Tower       Cancel Notice
Address                            1 Tower Lane                 Cancelation Comments
City                               Oakbrook Terrace
State                              IL                           First Refusal Comments
Zip                                60181
Office Type                        Regular
Lease Type                         original                     First Offer Comments
Lease Status                       active
Occupancy Status                   occupied                     Other Options Notes
Occupancy Type                     mixed
First in Location                  10/15/1996
Site Notes                         40,000 square feet -
                                    warehouse space             Rent Escalation Type               fixed
                                                                Escalation Comments                See rent schedule
Premises Notes                     40,000 square feet for
                                    warehouse space,

                                                                Late Charge Notes                  Prime - 3% Late fee.
Lease Date                         01/07/1996
Term                               78
Commence                           10/15/1996                   Holdover                           150%
Expire                             04/14/2003                   Expense Type                       gross
Deposit                            $0.00                        Code method                        none
Deposit Comments                                                Est. Mo Exp.                       $1,624.91
                                                                Last Update                        01/01/1997
                                                                Expense Notes                      Tenant responsible for clearing
                                                                                                    and HVAC costs.
Landlord Contact
Company                            Oakbrook Tower Limited
                                    Partnership
Address 1                          C/O M&M Realty Corporation,
                                    General Partners            Pay Taxes When Due?                Yes
Address 2                                                       Estimated Tax                      $19,499.00
City                                                            Property Tax Notes                 Tenant to pay 50% of real estate
                                                                                                    taxes assessed against
                                                                                                    warehouse.
State
Zip
Phone                                                           Parking Notes
Fax
Landlord Notes
                                                                Assignment/Sublet Notes            Prior written consent of LL is
                                                                                                    needed. Can sublet to
                                                                                                    subsidiary/affiliate without
                                                                                                    LL's consent.
Rent Contact                      George Rumel
Same As Landlord?                  No                           Misc, Lease Notes
Company                            Miglin-Beitler Management
PS Vendor #                        MIGLIN
Address 1                          C/O LaSalle National Bank    # Empl.
Address 2                          135 LaSalle St. Dept 3057    Open Ofc/Wksta
City                               Chicago
State                              IL                           Platinum Contact (1)
Zip                                60674-3057                   Contact's Title (1)
Phone                              (830) 571-8757               Phone (1)
Fax                                                             Fax (1)
Real Contact Notes                                              Platinum Contact (2)
                                                                Contact's Title (2)
                                                                Phone (2)
Legal Contact                                                   Fax (2)
Same As Landlord?                  Yes                          Platinum Contacts Notes
Company
Address 1
Address 2                                                       Broker ID
City                                                            Contact
State                                                           Company
Zip                                                             Address 1
Phone                                                           Address 2
Fax                                                             City
Legal Contact Notes                                             State
                                                                Zip
                                                                Phone
Improvement Type                   allowance                    Fax
LL Allowance                       $400,000.00                  Notes
Important Notes
</TABLE>


<TABLE>
<CAPTION>
Rent Period      Rent Start      Rent End        Mo. Rent        Abatement       Abated Rent       Real Notes
------------------------------------------------------------------------------------------------------------------------------------
<S>              <C>             <C>            <C>              <C>             <C>               <C>
    1            10/15/1996     12/31/1996      $25,166.67                       $25,166.67        Expenses include real taxes only.
    2            01/01/1997     12/31/1997      $26,166.67                       $26,166.67        Expenses include real taxes only.
    3            01/01/1998     12/31/1998      $27,233.33                       $27,233.33        Expenses include real taxes only.
    4            01/01/1999     12/31/1999      $28,300.00                       $28,300.00        Expenses include real taxes only.
    5            01/01/2000     12/31/2000      $29,433.33                       $29,433.33        Expenses include real taxes only.
    6            01/01/2001     12/31/2001      $30,633.33                       $30,633.33        Expenses include real taxes only.
    7            01/01/2002     12/31/2002      $31,833.33                       $31,833.33        Expenses include real taxes only.
    8            01/01/2003     12/31/2003      $33,133.33                       $33,133.33        Expenses include real taxes only.
</TABLE>

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