So if @ARGV contains the equivalent of, say, ('-Mstrict', '-Mdiagnostics'), PERL_moreoptions() sees this as if the elements were joined together? If so, I agree that that is a huge implementation flaw. It's perfectly valid to have ('-Mmodule qw(foo bar)', '-Mstrict'), which is what -M'module qw(foo bar)' would have given you, but joining them together loses the ability to differentiate. :(