diff --git a/mrbgems/mruby-time/src/time.c b/mrbgems/mruby-time/src/time.c
index 001d46b7c..518fb3d61 100644
--- a/mrbgems/mruby-time/src/time.c
+++ b/mrbgems/mruby-time/src/time.c
@@ -83,6 +83,12 @@ double round(double x) {
 
 /** end of Time class configuration */
 
+/* protection against incorrectly defined _POSIX_TIMERS */
+#if (_POSIX_TIMERS + 0) == 0
+#undef _POSIX_TIMERS
+#define _POSIX_TIMERS 0
+#endif
+
 #if (defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0) && defined(CLOCK_REALTIME)
 # define USE_CLOCK_GETTIME
 #endif