Is there a reason you use the unsightly-long name "system" instead of backticks (
$^O=~Win?`CLS`:`clear`;)? Does it get "Eye-dropped" in less characters? If you're hard-pressed for characters, you could probably also get away with
$^O=~W to test for Windows -- I can't think of another system with a capital 'W' in its name off-hand.
/s