#if defined(WINDOWS) || defined(__CYGWIN__)
# define PTIMER_WINDOWS /* use Windows timers */
#else
-# if _POSIX_TIMERS > 0
+# if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
# define PTIMER_POSIX /* use POSIX timers (clock_gettime) */
# else
# ifdef HAVE_GETTIMEOFDAY