diff --git a/src/unicode.c b/src/unicode.c
index 4dbfa6b..3bbf70f 100644
--- a/src/unicode.c
+++ b/src/unicode.c
@@ -11,6 +11,8 @@
  *-------------------------------------------------------------------------
  */
 
+#define _GNU_SOURCE 1
+#include <sys/types.h>
 #include <stdbool.h>
 
 #include "unicode.h"