diff --git a/src/fils.c b/src/fils.c
index ff8c1d6c..69346ed1 100644
--- a/src/fils.c
+++ b/src/fils.c
@@ -25,6 +25,8 @@
 #include <config.h>
 #endif
 
+#define _GNU_SOURCE
+#include <stdlib.h>
 #include <ell/ell.h>
 
 #include "ell/useful.h"