From: Hayashi Naoyuki I tried to compile with gcc on Tru64, and got the following error. SDL_systimer.c:45:45: error: operator '&&' has no right operand It succeeds if changing #if (defined _POSIX_TIMERS && _POSIX_TIMERS > 0) to #if (defined _POSIX_TIMERS && _POSIX_TIMERS + 0 > 0)