User Points are Beeing ignored if Entered as Decimal with Comma

I know that userpoints module does not support decimal numbers. But if you enter user points manually for an user and try to use the decimal comma "," instead of an decimal point (like german users do), the entry will be ignored. So, entering "1,5" gives no user points (and no error message) while "1.5" give the user 1 point. In both cases the module should give a warning or error message.