...
      my $extension = substr($element, -3) || '';
      if ( $extension eq 'exe' ) {
      ...
      elsif ( $extension eq 'dll' )
      ...

##</code><code>##

      ...
      my $extension = substr($element, -4);
      if ( $extension eq '.exe' ) {
      ...
      elsif ( $extension eq '.dll' )
      ...