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                                      FIRST

                             SUPPLEMENTAL INDENTURE

                                      AMONG

                       WILLIAMS SCOTSMAN, INC., as Issuer,

                           WILLSCOT EQUIPMENT, LLC and

                        SPACE MASTER INTERNATIONAL, INC.,

                        THE BANK OF NEW YORK, as Trustee


                       ----------------------------------

                          9 7/8% Senior Notes due 2007





Dated as of September 1, 1998

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         THIS FIRST SUPPLEMENTAL INDENTURE, dated as of September 1, 1998, among
Williams Scotsman, Inc., a Maryland corporation (the "Issuer"), Willscot
Equipment, LLC, a Delaware corporation ("Willscot"), Space Master International,
Inc., a Georgia corporation ("New Guarantor"), and The Bank of New York (the
"Trustee").

         WHEREAS, the Issuer, Mobile Field Office Company, a New Jersey
corporation ("MFO"), Willscot and the Trustee entered into an Indenture dated as
of May 15, 1997 (the "Indenture") to provide for the issuance of the Issuer's
9 7/8% Notes due June 1, 2007 (the "Notes");

         WHEREAS, on December 31 1997, MFO merged with the Issuer and ceased to
be a Guarantor;

         WHEREAS, on September 1, 1998, the Issuer entered into a transaction to
acquire all of the outstanding stock of Space Master International, Inc. (the
"Acquisition");

         WHEREAS, to finance the Acquisition, Scotsman Holdings, Inc.
("Holdings"), the Issuer, the financial institutions named therein as lenders,
Bankers Trust Company as issuing bank, BT Commercial Corporation, as
administrative agent and co-syndication agent, NationsBank, N.A., as
co-syndication agent, and Goldman Sachs Credit Partners L.P., as documentation
agent, are entering into a Credit Agreement, dated as of May 22, 1997, as
amended and restated as of September 1, 1998 (the "Credit Agreement");

         WHEREAS, the New Guarantor has guaranteed the obligations of the Issuer
under the Credit Agreement;

         WHEREAS, pursuant to Section 4.15 of the Indenture, by reason of such
guarantee the New Guarantor is required to execute this Supplemental Indenture
(this "Supplemental Indenture");

         WHEREAS, the Issuer, Willscot, the New Guarantor and the Trustee are
authorized to enter into this Supplemental Indenture;

         NOW, THEREFORE, for and in consideration of the premises and the mutual
covenants contained herein and in this Supplemental Indenture and for other good
and valuable consideration, the receipt and sufficiency of which are herein
acknowledged, the Issuer, Willscot, the Trustee and the New Guarantor hereby
agree for the equal and the ratable benefit of all holders of the Notes as
follows:


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                                   ARTICLE ONE

                                   DEFINITIONS

         1.1   DEFINITIONS. For purposes of this Supplemental Indenture, the
terms defined in the recitals shall have the meanings therein specified; any
terms defined in the Indenture and not defined herein shall have the same
meanings herein as therein defined; and references to Articles or Sections
shall, unless the context indicates otherwise, be references to Articles or
Sections of the Indenture.


                                   ARTICLE TWO

                               GUARANTEE OF NOTES

         2.1   UNCONDITIONAL GUARANTEE.

         Subject to the provisions of this Article Two, the New Guarantor
hereby, jointly and severally, unconditionally and irrevocably guarantees, on a
senior basis (such guarantee to be referred to herein as a "Guarantee") to each
Holder of a Note authenticated and delivered by the Trustee and to the Trustee
and its successors and assigns, irrespective of the validity and enforceability
of the Indenture, the Notes or the obligations of the Issuer or any other
Guarantor to the Holders or the Trustee thereunder, that: (a) the principal of,
premium, if any, and interest on the Notes (and any Additional Interest payable
thereon) shall be duly and punctually paid in full when due, whether at
maturity, upon redemption, upon repurchase at the option of Holders pursuant to
the provisions of the Notes relating thereto, by acceleration or otherwise, and
interest on the overdue principal and (to the extent permitted by law) interest,
if any, on the Notes and all other obligations of the Issuer or the New
Guarantor to the Holders or the Trustee thereunder or under the Indenture
(including amounts due to the Trustee under Article 7.07 of the Indenture) and
all other obligations shall be promptly paid in full or performed, all in
accordance with the terms hereof and thereof; and (b) in case of any extension
of time of payment or renewal of any Notes or any of such other obligations, the
same shall be promptly paid in full when due or performed in accordance with the
terms of the extension or renewal, whether at maturity, by acceleration or
otherwise. Failing payment when due of any amount so guaranteed, or failing
performance of any other obligation of the Issuer to the Holders under the
Indenture or under the Notes, for whatever reason, the New Guarantor shall be
obliged to pay, or to perform or cause the performance of, the same immediately.
An Event of Default under the Indenture or the Notes shall constitute an event
of default under this Guarantee, and shall entitle the Holders of Notes to
accelerate the obligations of the New Guarantor hereunder in the same manner and
to the same extent as the obligations of the Issuer.

         The New Guarantor hereby agrees that its obligations hereunder shall be
unconditional, irrespective of the validity, regularity or enforceability of the
Notes or the Indenture, the absence of any action to enforce the same, any
waiver or consent by any Holder of the Notes with respect to any provisions
hereof or of the Notes or the Indenture, any release of any other Guarantor, the
recovery of any judgment against the Issuer, any action to enforce the same,
whether or not a Guarantee is affixed to any particular Note, or any other
circumstance which might otherwise constitute a legal or equitable discharge or
defense of the New Guarantor. To the fullest extent permitted by law, the New
Guarantor hereby waives the benefit of diligence, presentment, demand of

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payment, filing of claims with a court in the event of insolvency or bankruptcy
of the Issuer, any right to require a proceeding first against the Issuer,
protest, notice and all demands whatsoever and covenants that its Guarantee
shall not be discharged except by complete performance of the obligations
contained in the Notes, the Indenture and this Guarantee. The Guarantee is a
guarantee of payment and not of collection. If any Holder or the Trustee is
required by any court or otherwise to return to the Issuer or to any Guarantor,
or any custodian, trustee, liquidator or other similar official acting in
relation to the Issuer or the New Guarantor, any amount paid by the Issuer or
any Guarantor to the Trustee or such Holder, the Guarantee, to the extent
theretofore discharged, shall be reinstated in full force and effect. The New
Guarantor further agrees that, as between it, on the one hand, and the Holders
of Notes and the Trustee, on the other hand, (a) subject to this Article Two,
the maturity of the obligations guaranteed hereby may be accelerated as provided
in Article Six of the Indenture for the purposes of the Guarantee,
notwithstanding any stay, injunction or other prohibition preventing such
acceleration in respect of the obligations guaranteed hereby, and (b) in the
event of any acceleration of such obligations as provided in Article Six of the
Indenture, such obligations (whether or not due and payable) shall forthwith
become due and payable by the New Guarantor for the purpose of this Guarantee.

         If the New Guarantor makes a payment or distribution under its
Guarantee, it shall be entitled to a contribution from each other Guarantor in
an amount pro rata based on the net assets of each Guarantor determined in
accordance with GAAP.

         2.2   LIMITATIONS ON GUARANTEES.

         The obligations of the New Guarantor under its Guarantee are limited to
the maximum amount which, after giving effect to all other contingent and fixed
liabilities of the New Guarantor (including, without limitation, its guarantee
of all obligations pursuant to the Credit Agreement) and after giving effect to
any collections from or payments made by or on behalf of any other Guarantor in
respect of the obligations of such other Guarantor under its Guarantee or
pursuant to its contribution obligations under the Indenture, will result in the
obligations of the New Guarantor under the Guarantee not constituting a
fraudulent conveyance or fraudulent transfer under any laws of the United State,
any state of the United States or the District of Columbia.

         2.3   EXECUTION AND DELIVERY OF GUARANTEE.

         To further evidence the Guarantee set forth in Article 2.1 the New
Guarantor hereby agrees that a notation of such Guarantee substantially in the
form of Exhibit E of the Indenture, shall be endorsed on each Note authenticated
and delivered by the Trustee; provided however, that any Note delivered by the
Trustee prior to the date of this Supplemental Indenture shall not be required
to be amended to note this Guarantee and that the Guarantee of the New Guarantor
shall hereby be effective for all such Notes from the date of this Supplemental
Indenture. Such Guarantee shall be executed on behalf of the New Guarantor and
by either manual or facsimile signature of two Officers of the New Guarantor
each of whom shall have been duly authorized to so execute by all

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requisite corporate or other action. The validity and enforceability of the
Guarantee shall not be affected by the fact that it is not affixed to any
particular Note.

         The New Guarantor hereby agrees that its Guarantee, set forth in
Article 2.1, shall remain in full force and effect notwithstanding any failure
to endorse on each Note a notation of such Guarantee.

         If an Officer of the New Guarantor whose signature is on the Indenture
or a Guarantee, no longer holds that office at the time the Trustee
authenticates the Notes of which such Guarantee is endorsed or at any time
thereafter, the New Guarantor's Guarantee of such Notes shall be valid
nevertheless.

         The delivery of any Note by the Trustee, after the authentication
thereof under the Indenture, shall constitute due delivery of the Guarantee set
forth in the Indenture on behalf of the New Guarantor.

         2.4   OTHER PROVISIONS OF THE INDENTURE.

         The parties hereby agree that all the provisions of the Indenture that
relate to a Guarantor and Guarantee (including, without limitation, Sections
11.05 to 11.22 of the Indenture) shall apply to the New Guarantor and its
Guarantee provided hereunder.

         2.5   NO PERSONAL LIABILITY.

         No stockholder, officer, director, employee or incorporator, past,
present or future, of the New Guarantor, as such, shall have any personal
liability under the Guarantee by reason of his, her or its status as such
stockholder, officer, director, employee or incorporator.


                                  ARTICLE THREE

                                  MISCELLANEOUS

         3.1   EFFECT OF THE SUPPLEMENTAL INDENTURE. This Supplemental Indenture
supplements the Indenture and shall be a part and subject to all the terms
thereof. Except as supplemented hereby, the Indenture and the Notes issued
thereunder shall continue in full force and effect.

         3.2   COUNTERPARTS. This Supplemental Indenture may be executed in
counterparts, each of which shall be deemed an original, but all of which shall
together constitute one and the same instrument.

         3.3   GOVERNING LAW. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY,
AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK, AS APPLIED
TO CONTRACTS MADE AND PERFORMED WITHIN THE STATE OF NEW YORK, WITHOUT REGARD TO
PRINCIPLES OF CONFLICTS OF LAWS. Each of the parties hereto agrees to submit to
the jurisdiction of the courts of the State of New York in any action or

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proceeding arising out of or relating to this Supplemental Indenture, the
Indenture, the Notes, the Guarantee or the Subordinated Guarantee.

         3.4   RECITALS. The Trustee shall not be responsible for any recital
herein (other than the fifth recital as it applies to the Trustee) as such
recitals shall be taken as statements of the Issuer, or the validity of the
execution by the New Guarantor of this Supplemental Indenture. The Trustee makes
no representations as to the validity or sufficiency of this Supplemental
Indenture.



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         IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed, and their respective corporate seals to be
hereunto affixed and attested, all as of the date first written above.


                                      WILLIAMS SCOTSMAN, INC.


                                      By: /S/ GERARD E. HOLTHAUS
                                          ----------------------------
                                          Name:  Gerard E. Holthaus
                                          Title: President


                                      WILLSCOT EQUIPMENT, LLC


                                      By: /S/ GERARD E. HOLTHAUS
                                          ----------------------------
                                          Name:  Gerard E. Holthaus
                                          Title: President



                                      SPACE MASTER INTERNATIONAL, INC.


                                      By: /S/ GERARD E. HOLTHAUS
                                          ----------------------------
                                          Name:  Gerard E. Holthaus
                                          Title: President



                                      THE BANK OF NEW YORK, as Trustee


                                      By: /S/ MARY BETH LEWICKI
                                          ----------------------------
                                          Name:  Mary Beth Lewicki
                                          Title: Assistant Vice President