diff -uNr tcc-0.9.26.orig/tcc.h tcc-0.9.26-1gnusourcesafety/tcc.h
--- tcc-0.9.26.orig/tcc.h	2013-02-15 08:24:00.000000000 -0600
+++ tcc-0.9.26-1gnusourcesafety/tcc.h	2014-05-02 10:45:54.576640002 -0500
@@ -21,7 +21,9 @@
 #ifndef _TCC_H
 #define _TCC_H
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include "config.h"
 
 #ifdef CONFIG_TCCBOOT
