--- a/SConstruct
+++ b/SConstruct
@@ -744,11 +744,13 @@ typedef int clockid_t;
 # endif
 /* OS X uses _STRUCT_TIMESPEC, but no clock_gettime */
 #ifndef _STRUCT_TIMESPEC
+#ifndef __timespec_defined
 struct timespec {
     time_t  tv_sec;
     long    tv_nsec;
 };
 #endif
+#endif
 #define CLOCK_REALTIME	0
 int clock_gettime(clockid_t, struct timespec *);
 # ifdef __cplusplus