--- a/util-src/signal.c	Wed Aug 08 08:19:01 2018 +0100
+++ b/util-src/signal.c	Wed Aug 08 09:27:34 2018 +0200
@@ -26,7 +26,9 @@
  * OTHER DEALINGS IN THE SOFTWARE.
 */
 
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 
 #include <signal.h>
 #include <stdlib.h>