I have a link like:

domain.com/foo/bar?f[0]=region%3A81&f[1]=product%3A561

I'm running HTTrack with httrack  -N "%h%p/%n%k"

This returns 

domain.com/foo/bar_f[0]=region%3A81&f[1]=product%3A561

The question mark is converted to an underscore?
Is there any way to prevent this?
Thanks!
Jim