Some of our users experience problems setting some files size limits, such as attachment quotas.
On 32-bit servers it's impossible for now to set quota >= 2048 MiB, because phpBB3 uses bitwise operatoins to set it. If you try to set, say, 2048 MiB attachment quota, it results in value -2147483648.

Don't know if it either is a bug or intended behaviour, but I thought it's worth to be noticed