--- posix.c	2008-05-04 14:39:48.000000000 -0700
+++ posix.c	2008-11-20 21:01:26.234375000 -0800
@@ -22,7 +22,9 @@
 #endif
 
 /* Make GNU/Linux libc declare everything it has. */
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 
 #include <stdio.h>
 #include <errno.h>