Recent versions of Perl (v5.24.1+) removed '.' from @INC, so this is probably right on the mark. If the OP is using a recent enough Perl version it will not look in the dot path unless something like this happens:
use lib '.';
Though that is subject to the challenges that the dot path has always faced. It would be better to do something like this:
use lib "$FindBin::Bin/../lib"; # Or whatever is accurate for this scr
This eliminates sensitivity to where the script was invoked from.
See also: FindBin, lib, and perl5241delta.