--- a/src/ipset.c
+++ b/src/ipset.c
@@ -6,8 +6,8 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
-#define _GNU_SOURCE
 #include <assert.h>			/* assert */
+#include <libgen.h>			/* basename */
 #include <stdio.h>			/* fprintf */
 #include <stdlib.h>			/* exit */
 #include <string.h>			/* strcmp */
