Oof, you're right, thank you. In my mind the last byte was obviously zero for a heap string too, since the pointer or sizes would've had a zero upper byte. Some

Oof, you're right, thank you. In my mind the last byte was obviously zero for a heap string too, since the pointer or sizes would've had a zero upper byte. Somehow I never accounted for the fact that on 64-bit there's no need to represent it that way. Fantastic point!