diff --git a/headers/posix/wchar.h b/headers/posix/wchar.h
index 93042b0224..3cc6fc1063 100644
--- a/headers/posix/wchar.h
+++ b/headers/posix/wchar.h
@@ -4,5 +4,14 @@
  *
  * Distributed under the terms of the MIT license
  */
+#ifndef _WCHAR_H
+#define _WCHAR_H
 
 #include <wchar_t.h>
+
+#include <size_t.h>
+
+int		mbsinit(const mbstate_t *);
+size_t	wcrtomb(char *, wchar_t, mbstate_t *);
+
+#endif /* _WCHAR_H */