Good point, duly noted.
In this case, I don't think this could be the issue as I the test was done on files with a lower-case extension.

To be honest, even though I'm sure File::Spec is in principle a better solution than what I'm doing, I'm reluctant to learn how File::Spec works, rewrite the script and then start testing/troubleshooting on all platforms all over again. What I have works on Windows and Linux, I'd be more inclined to just fix the current OS X problems and call it a day... if the problems are easily fixable, that is.