Yeah, you pretty much need to treat a millisecond timestamp as an opaque value, only using the Int you get when you subtract two of them. Doing that completely

Yeah, you pretty much need to treat a millisecond timestamp as an opaque value, only using the Int you get when you subtract two of them. Doing that completely avoids the issues from timestamps being negative or wrapping around. I've seen games that crash if your timestamps were negative. So if your computer has been on for a while, and a game isn't running properly, reboot.