C:\Perl\X11-GUITest-0.20>nmake install

Microsoft (R) Program Maintenance Utility   Version 1.50
Copyright (c) Microsoft Corp 1988-94. All rights reserved.

        cl -c -I/usr/X11R6/include -I/usr/X/include -Wall -O2    -DVERSION=\"0.20\"  -DXS_VERSION=\"0.20\"  -IC:\Perl\lib\CORE -DNDEBUG GUITest.c
'cl' is not recognized as an internal or external command, operable program or batch file.
NMAKE : fatal error U1077: 'C:\WINNT\system32\cmd.exe' : return code '0x1'
Stop.