UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                               (Amendment No. 1   )*
                                            -------

                            TIDEL TECHNOLOGIES, INC.
                                (Name of Issuer)

                                  Common Stock
--------------------------------------------------------------------------------
                         (Title of Class of Securities)


                                    886368109
                  ---------------------------------------------
                                 (CUSIP Number)



                                December 31, 2001
         --------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)


     Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:

                                [x] Rule 13d-1(b)
                                [_] Rule 13d-1(c)
                                [_] Rule 13d-1(d)



*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).

                               Page 1 of 9 Pages



--------------------------                          --------------------------
  CUSIP NO.  886368109               13G             Page 2 of 9 Pages
           ---------                                --------------------------
------------------------------------------------------------------------------
      NAMES OF REPORTING PERSON
 1    S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

        Liberty Wanger Asset Management, L.P. 36-3820584

------------------------------------------------------------------------------
      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
 2                                                              (a) [_]
        Not Applicable                                          (b) [_]

------------------------------------------------------------------------------
      SEC USE ONLY
 3
------------------------------------------------------------------------------
      CITIZENSHIP OR PLACE OF ORGANIZATION
 4
        Delaware

------------------------------------------------------------------------------
                          SOLE VOTING POWER
                     5
     NUMBER OF              None
      SHARES       -----------------------------------------------------------
                          SHARED VOTING POWER
   BENEFICIALLY      6
     OWNED BY               0
                   -----------------------------------------------------------
       EACH               SOLE DISPOSITIVE POWER
                     7
    REPORTING               None
      PERSON       -----------------------------------------------------------
                          SHARED DISPOSITIVE POWER
       WITH          8
                            0
------------------------------------------------------------------------------
      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 9
        0
------------------------------------------------------------------------------
      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
10
        Not Applicable                                              [_]

------------------------------------------------------------------------------
      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
11
        0.0%

------------------------------------------------------------------------------
      TYPE OF REPORTING PERSON*
12
        IA
------------------------------------------------------------------------------
                      *SEE INSTRUCTION BEFORE FILLING OUT!




--------------------------                           --------------------------
  CUSIP No.  886368109                13G              Page 3 of 9 Pages
            ----------
--------------------------                           --------------------------
------------------------------------------------------------------------------
      NAME OF REPORTING PERSON
 1    S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

      WAM Acquisition GP, Inc.

------------------------------------------------------------------------------
      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
 2                                                              (a) [_]
      Not Applicable                                            (b) [_]

------------------------------------------------------------------------------
      SEC USE ONLY
 3

------------------------------------------------------------------------------
      CITIZENSHIP OR PLACE OF ORGANIZATION
 4
      Delaware

------------------------------------------------------------------------------
                          SOLE VOTING POWER
                     5
     NUMBER OF            None

      SHARES       -----------------------------------------------------------
                          SHARED VOTING POWER
   BENEFICIALLY      6

     OWNED BY             0

                   -----------------------------------------------------------
       EACH               SOLE DISPOSITIVE POWER
                     7
    REPORTING             None

      PERSON       -----------------------------------------------------------
                          SHARED DISPOSITIVE POWER
       WITH          8
                          0

------------------------------------------------------------------------------
      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
 9
      0

------------------------------------------------------------------------------
      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
10
      Not Applicable                                                [_]

------------------------------------------------------------------------------
      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
11
      0.0%

------------------------------------------------------------------------------
      TYPE OF REPORTING PERSON*
12
      CO

------------------------------------------------------------------------------
                      *SEE INSTRUCTION BEFORE FILLING OUT!



Item 1(a)      Name of Issuer:

                        Tidel Technologies, Inc.


Item 1(b)      Address of Issuer's Principal Executive Offices:

                        5847 San Felipe, Suite 900
                        Houston, Texas 77057


Item 2(a)      Name of Person Filing:

                        Liberty Wanger Asset Management, L.P. ("WAM")
                        WAM Acquisition GP, Inc., the general partner of WAM
                         ("WAM GP")


Item 2(b)      Address of Principal Business Office:

                        WAM and WAM GP are located at:

                        227 West Monroe Street, Suite 3000
                        Chicago, Illinois  60606


Item 2(c)      Citizenship:

                        WAM is a Delaware limited partnership; and WAM GP is a
                        Delaware corporation.

Item 2(d)      Title of Class of Securities:

                        Common Stock

Item 2(e)      CUSIP Number:

                        886368109

Item 3         Type of Person:

                        (e)    WAM is an Investment Adviser registered under
                               section 203 of the Investment Advisers Act of
                               1940; WAM GP is the General Partner of the
                               Investment Adviser.

                                Page 4 of 9 pages



Item 4    Ownership (at December 31, 2001):

               (a)   Amount owned "beneficially" within the meaning of rule
                     13d-3:

                     0

               (b)   Percent of class:

                     0.0% (based on 17,426,210 shares outstanding as of January
                     7, 2002)

               (c)   Number of shares as to which such person has:

                         (i)   sole power to vote or to direct the vote: none

                        (ii)   shared power to vote or to direct the vote: 0

                       (iii)   sole power to dispose or to direct the
                               disposition of: none

                        (iv)   shared power to dispose or to direct disposition
                               of: 0


Item 5    Ownership of Five Percent or Less of a Class:

               If this statement is being filed to report the fact that as of
               the date hereof the reporting person has ceased to be the
               beneficial owner of more than five percent of the class of
               securities, check the following: [x]

Item 6    Ownership of More than Five Percent on Behalf of Another Person:

               Not Applicable

Item 7    Identification and Classification of the Subsidiary Which Acquired
          the Security Being Reported on by the Parent Holding Company:

               Not Applicable

Item 8    Identification and Classification of Members of the Group:

               Not Applicable

Item 9    Notice of Dissolution of Group:

               Not Applicable

                               Page 5 of 9 Pages



Item 10   Certification:

               By signing below I certify that, to the best of my knowledge and
          belief, the securities referred to above were acquired and are held in
          the ordinary course of business and were not acquired and are not held
          for the purpose of or with the effect of changing or influencing the
          control of the issuer of the securities and were not acquired and are
          not held in connection with or as a participant in any transaction
          having that purpose or effect.

                               Page 6 of 9 Pages



                                    Signature
                                    ---------

     After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

Date: February 8, 2002


                    The undersigned corporation, on the date above written,
                    agrees and consents to the joint filing on its behalf of
                    this Schedule 13G in connection with its beneficial
                    ownership of the security reported herein.

                                      WAM Acquisition GP, Inc.
                                          for itself and as general partner of
                                          LIBERTY WANGER ASSET MANAGEMENT, L.P.



                                      By: /s/ Bruce H. Lauer
                                          -------------------------------------
                                          Bruce H. Lauer
                                          Senior Vice President and Secretary

                               Page 7 of 9 Pages



                                  Exhibit Index
                                  -------------


Exhibit 1               Joint Filing Agreement dated as of February 8, 2002
                        between Liberty Wanger Asset Management, L.P. and WAM
                        Acquisition GP, Inc.

                               Page 8 of 9 Pages



                                                                       EXHIBIT 1

                             JOINT FILING AGREEMENT

     The undersigned hereby agree to the joint filing of the Schedule 13G to
which this Agreement is attached.


                         Dated: February 8, 2002


                                                 WAM Acquisition GP, Inc.
                                                     for itself and as general
                                                     partner o fLIBERTY WANGER
                                                     ASSET MANAGEMENT, L.P.



                                                 By: /s/ Bruce H. Lauer
                                                     ---------------------------
                                                         Bruce H. Lauer
                                                         Senior Vice President
                                                          and Secretary

                               Page 9 of 9 pages