prove's -l (lowercase "L") appends ./lib to @INC. So, prove -l, might do what you want. Similarly, prove -It/lib would work for you it seems. That said, .pm files in ./t should probably be in ./t/lib or /xlib. Using Dist::Zilla, you could also have a proper lib/Test/ namespace, then strip out what you don't want to include in the actual distribution. YMMV