diff --git a/src/core/wee-utf8.c b/src/core/wee-utf8.c
index 17f6c20..c04e6fe 100644
--- a/src/core/wee-utf8.c
+++ b/src/core/wee-utf8.c
@@ -23,9 +23,13 @@
 #include "config.h"
 #endif
 
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE 1
+#endif
+
 #include <stdlib.h>
 #include <string.h>
-
+#include <wchar.h>
 #include "weechat.h"
 #include "wee-utf8.h"
 #include "wee-config.h"