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                                                                     EXHIBIT 4.C


                       FIRST AMENDMENT TO RIGHTS AGREEMENT

        FIRST AMENDMENT (this "Amendment") to the Rights Agreement, dated as of
March 17, 1998 (the "Rights Agreement"), between ABM Industries Incorporated, a
Delaware corporation (the "Company"), and Mellon Investor Services LLC (f/k/a
ChaseMellon Shareholder Services, L.L.C.), as Rights Agent (the "Rights Agent"),
made and entered into as of May 6, 2002.

                              W I T N E S S E T H:

        WHEREAS, the Company and the Rights Agent entered into the Rights
Agreement specifying the terms of the Rights; and

        WHEREAS, all acts and things necessary to constitute this Amendment a
valid agreement according to its terms have been done and performed, and the
execution and delivery by the Company and the Rights Agent of this Amendment
have in each and all respects been fully authorized by the Company and the
Rights Agent;

        NOW THEREFORE, in consideration of the promises and the respective
agreements set forth herein, the parties hereby agree as follows:

        1. In Section 1.1 of the Rights Agreement, the definition of "Redemption
Price" shall be, and is hereby amended in its entirety to read as follows:

        "'Redemption Price' shall mean an amount equal to one-half cent
        ($0.005) per Right, as such amount may be appropriately adjusted to
        reflect any stock split, stock dividend or similar transaction
        occurring after the date hereof."

        2. Section 2.3(a) of the Rights Agreement shall be, and is hereby
amended in its entirety to read as follows:

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                "(a) Subject to Sections 3.1, 5.1 and 5.10 and subject to
        adjustment as herein set forth, each Right will entitle the holder
        thereof, after the Separation Time and prior to the Expiration Time, to
        purchase, for the Exercise Price, one two-thousandth (1\2000) of a share
        of Preferred Stock."

        3. Section 3.1(d) of the Rights Agreement shall be, and is hereby
amended in its entirety to read as follows:

                "(d) Whenever the Company shall become obligated under Section
        3.1(a) or (c) to issue shares of Common Stock upon exercise of or in
        exchange for Rights, the Company, at its option, may substitute
        therefore shares of Preferred Stock, at a ratio of one two-thousandth of
        a share of Preferred Stock for each share of Common Stock so issuable,
        appropriately adjusted to protect interests of the holders of the Rights
        generally to reflect any event of this type analogous to any of the
        events described in Section 2.4 (a) or (b) which my have occurred with
        respect to the Common Stock."

        4. Exhibit A of the Rights Agreement shall be, and hereby is amended as
follows:

                (a) The words ", AS AMENDED" shall be, and are hereby added to
        the first sentence of the legend at the top of page A-1 after the words
        "RIGHTS AGREEMENT".

                (b) The first full paragraph under the heading "Rights
        Certificate" shall be, and is hereby is amended by deleting the words
        "one one-thousandth of a fully paid share" and substituting in lieu
        thereof the words "two one-thousandths of a fully paid share."

                (c) The fifth full paragraph under the heading "Rights
        Certificate" shall be, and is hereby is amended by deleting the words
        "$0.01 per Right" and substituting in lieu thereof the words "$0.005 per
        Right."

        5. Except as amended hereby, the Rights Agreement shall continue in full
force and effect.

        6. This Amendment may be executed in any number of counterparts and each
of such counterparts shall for all purposes be deemed to be an original, and all
such counterparts shall together constitute but one and the same instrument.


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        7. This Amendment shall be deemed to be a contract made under the laws
of the State of Delaware and for all purposes shall be governed by and construed
in accordance with the laws of such state applicable to contracts to be made and
performed entirely within such State.

        8. Terms used in this Amendment and not defined herein shall have the
meanings assigned to such terms by the Rights Agreement.

        9. If any term or provision hereof or the application thereof to any
circumstance shall, in any jurisdiction and to any extent, be invalid or
unenforceable, such term or provision shall be ineffective as to such
jurisdiction to the extent of such invalidity or unenforceability without
invalidation or rendering unenforceable the remaining terms and provisions of
this Amendment or the Rights Agreement or the application of such term or
provision to circumstances other than those as to which it is held invalid or
unenforceable.

        IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed as of the date first above written.

                                            ABM INDUSTRIES INCORPORATED



                                            By: /s/ Lorraine P. O'Hara
                                                --------------------------------
                                                Name:  Lorraine P. O'Hara
                                                Title: Assistant Secretary


                                            MELLON INVESTOR SERVICES LLC



                                            By: /s/ Sharon Magidson
                                                --------------------------------
                                                Name:  Sharon Magidson
                                                Title: Vice President



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