diff --git a/lib/libc/stdlib/strfmon.3 b/lib/libc/stdlib/strfmon.3
index 2427e35be873..2ede7cfaacd9 100644
--- a/lib/libc/stdlib/strfmon.3
+++ b/lib/libc/stdlib/strfmon.3
@@ -35,7 +35,7 @@
 .Sh SYNOPSIS
 .In monetary.h
 .Ft ssize_t
-.Fn strfmon "char *s" "size_t maxsize" "const char *format" "..."
+.Fn strfmon "char * restrict s" "size_t maxsize" "const char * restrict format" "..."
 .Sh DESCRIPTION
 The
 .Fn strfmon
diff --git a/lib/libc/stdlib/strfmon.c b/lib/libc/stdlib/strfmon.c
index aa9b31849413..d30f268356ca 100644
--- a/lib/libc/stdlib/strfmon.c
+++ b/lib/libc/stdlib/strfmon.c
@@ -88,7 +88,8 @@ static int __calc_left_pad(int, char *);
 static char *__format_grouped_double(double, int *, int, int, int);
 
 ssize_t
-strfmon(char *s, size_t maxsize, const char *format, ...)
+strfmon(char * __restrict s, size_t maxsize, const char * __restrict format,
+    ...)
 {
 	va_list		ap;
 	char 		*dst;		/* output destination pointer */