$ cat ../safe/script.pl
#!/usr/bin/perl -wT

BEGIN {
   # amend @INC without taint
   use FindBin;
   my $path = $FindBin::RealBin;
   $path =~ /^(.+)$/;
   $path = $1;
   my $relative_path = 'lib';
   unshift @INC, "$path/$relative_path";
}

use Module;

$ cat ../safe/lib/Module.pm
print("All's well\n");
1;