Huh. That never occurred to me (even though I spend a lot of my days writing code too).

In case you're expressing actual uncertainty rather than merely what your brain gets confused about, the answer is that a false positive is something that falsely looks positive. Perhaps the best way to put it is different, though: a false positive is a positive result of your test (so it actually is a positive) that doesn't match the underlying reality. Like a "false alarm".