diff --git a/tests/gtkgears.c b/tests/gtkgears.c
index d46f59876a..32a24dafb4 100644
--- a/tests/gtkgears.c
+++ b/tests/gtkgears.c
@@ -35,7 +35,6 @@
  * Jul 13, 2010
  */
 
-#define _GNU_SOURCE
 #include "config.h"
 
 #include <math.h>