diff --git a/man3/mbtowc.3 b/man3/mbtowc.3
index d0af36831..80058a192 100644
--- a/man3/mbtowc.3
+++ b/man3/mbtowc.3
@@ -20,7 +20,8 @@ mbtowc \- convert a multibyte sequence to a wide character
 .nf
 .B #include <stdlib.h>
 .PP
-.BI "int mbtowc(wchar_t *" pwc ", const char *" s ", size_t " n );
+.BI "int mbtowc(wchar_t *restrict " pwc ", const char *restrict " s \
+", size_t " n );
 .fi
 .SH DESCRIPTION
 The main case for this function is when