Stupid question- numberplate light screws

[Mopey]

Hi. My rear reverse camera is currently taped onto the car as the original screws fell out somehow! They are a right faf so not so keen on taking out the other side to measure as I’m not sure they will screw back in properly/ rusty as anything.
Does it matter what screws are used? I’m guessing they are 3.5 or 3mm by 12? They are only small.

Anyone else done it recently