diff --git a/library/include/wchar.h b/library/include/wchar.h
index fb8c39e..385b4ff 100644
--- a/library/include/wchar.h
+++ b/library/include/wchar.h
@@ -81,7 +81,7 @@ typedef long mbstate_t;
 extern wint_t btowc(int c);
 extern int wctob(wint_t c);
 extern int mbsinit(const mbstate_t *ps);
-extern size_t mbrlen(wchar_t *pwc, const char * s, size_t n, mbstate_t *ps);
+extern size_t mbrlen(const char *restrict s, size_t n, mbstate_t *restrict ps);
 extern size_t wcrtomb(char *s, wchar_t wc, mbstate_t *ps);
 extern size_t mbsrtowcs(wchar_t *pwcs, const char **src, size_t n, mbstate_t *ps);
 extern size_t wcsrtombs(char *s, const wchar_t **src, size_t n, mbstate_t *ps);
diff --git a/library/wchar_mbrlen.c b/library/wchar_mbrlen.c
index a777c14..b0d1c4d 100644
--- a/library/wchar_mbrlen.c
+++ b/library/wchar_mbrlen.c
@@ -38,7 +38,7 @@
 /****************************************************************************/
 
 size_t
-mbrlen(wchar_t *pwc, const char * s, size_t n, mbstate_t *ps)
+mbrlen(const char *restrict s, size_t n, mbstate_t *restrict ps)
 {
 	/* ZZZ unimplemented */
 	return(0);