Well...

I don't get it. I even copied your code to my local disk and it ran without problems (cygwin). Your code appears to be fine.

bash-3.00$ ./test.pl
x = 42
bash-3.00$
[download]

Maybe a reinstall of your Class::Std module could do the trick?

I have here:

Class-Std-0.0.4.tar.gz
Module-Build-0.2611.tar.gz
ExtUtils-MakeMaker-6.30.tar.gz
version-0.47.tar.gz