Tk800.013 has been built by the author using ActivePerl from ActiveState's APi509e.exe. You need Visual C++ (Mine is version 6.0 - Professional Edition). When you install ActivePerl, it provides patched C runtime as PerlCRT.dll which it installs in the "system32" directory. This needs "administrator" rights on NT. It also provides the import library PerlCRT.lib, but this is installed in an odd location e.g. C:\ActivePerl\lib\CORE\PerlCRT.lib where it is not found by MakeMaker or VC++. I copied it to C:\VisualStudio\VC98\lib\PerlCRT.lib (Your paths may vary dependinh where you installed ActivePerl and VC++.) Once that is done: perl Makefile.PL nmake nmake test nmake install_perl Works as expected. With prior verions of ActivePerl and Tk it has been necessary with some versions of VC++ to downgrade "optimization"; from -O2 that ActivePerl suggests, to -Od. This does not _seem_ to be required this time.