diff --git a/src/core/wcwidth-wrapper.c b/src/core/wcwidth-wrapper.c
index 8dd9dac7..03d0dc0c 100644
--- a/src/core/wcwidth-wrapper.c
+++ b/src/core/wcwidth-wrapper.c
@@ -18,7 +18,7 @@
     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
-#define _XOPEN_SOURCE
+#define _GNU_SOURCE
 #include <wchar.h>
 
 #include "module.h"