Your code works for me. Here is a command line version which doesn't differ in any important way, $ perl -MExtUtils::Installed -e'my $inst = ExtUtils::Installed->new(); print $_, $/ for $inst->modules' That prints the correct list, which includes "Perl" as one element. I'm at a loss to say why you don't get more. You seem to be finding the ExtUtils::Installed module ok.