Just FYI, "0E0" ("0 but true") evaluates to true in a boolean context but will still equal zero if you do a numeric test. So you don't have to do a string comparison against '0E0'. A simple if ($msg) { ... if ($msg == 0) { ... } } would work as you'd expect (for cases where you're testing), and forcing it to be numeric could easily be done just by adding zero ($msg += 0;) or printing it out via s?printf.