diff --git a/lib/libc/string/bstring.3 b/lib/libc/string/bstring.3
--- a/lib/libc/string/bstring.3
+++ b/lib/libc/string/bstring.3
@@ -29,7 +29,7 @@
 .\"
 .\"     @(#)bstring.3	8.1 (Berkeley) 6/4/93
 .\"
-.Dd June 4, 1993
+.Dd December 5, 2023
 .Dt BSTRING 3
 .Os
 .Sh NAME
@@ -58,7 +58,7 @@
 .Ft int
 .Fn memcmp "const void *b1" "const void *b2" "size_t len"
 .Ft void *
-.Fn memccpy "void *dst" "const void *src" "int c" "size_t len"
+.Fn memccpy "void * restrict dst" "const void * restrict src" "int c" "size_t len"
 .Ft void *
 .Fn memcpy "void *dst" "const void *src" "size_t len"
 .Ft void *
@@ -80,6 +80,7 @@
 .Xr memccpy 3 ,
 .Xr memchr 3 ,
 .Xr memcmp 3 ,
+.Xr memccpy 3 ,
 .Xr memcpy 3 ,
 .Xr memmove 3 ,
 .Xr memset 3
diff --git a/lib/libc/string/memccpy.3 b/lib/libc/string/memccpy.3
--- a/lib/libc/string/memccpy.3
+++ b/lib/libc/string/memccpy.3
@@ -27,7 +27,7 @@
 .\"
 .\"     @(#)memccpy.3	8.1 (Berkeley) 6/9/93
 .\"
-.Dd June 9, 1993
+.Dd December 5, 2023
 .Dt MEMCCPY 3
 .Os
 .Sh NAME
@@ -38,7 +38,7 @@
 .Sh SYNOPSIS
 .In string.h
 .Ft void *
-.Fn memccpy "void *dst" "const void *src" "int c" "size_t len"
+.Fn memccpy "void * restrict dst" "const void * restrict src" "int c" "size_t len"
 .Sh DESCRIPTION
 The
 .Fn memccpy
@@ -61,13 +61,30 @@
 Otherwise,
 .Fa len
 bytes are copied, and a NULL pointer is returned.
+If
+.Fa src
+and
+.Fa dst
+overlap, behavior is undefined.
 .Sh SEE ALSO
 .Xr bcopy 3 ,
 .Xr memcpy 3 ,
 .Xr memmove 3 ,
 .Xr strcpy 3
+.Sh STANDARDS
+The
+.Fn memccpy
+function conforms to
+.St -p1003.1-2004
+and
+.\" St -isoC-2024 .
+ISO/IEC 9899:2024 (\(lqISO\~C23\(rq).
 .Sh HISTORY
 The
 .Fn memccpy
 function first appeared in
 .Bx 4.4 .
+The
+.Ft restrict
+keyword was added to the prototype in
+.Fx 14.1 .
diff --git a/lib/libc/string/memccpy.c b/lib/libc/string/memccpy.c
--- a/lib/libc/string/memccpy.c
+++ b/lib/libc/string/memccpy.c
@@ -36,7 +36,7 @@
 #include <string.h>
 
 void *
-memccpy(void *t, const void *f, int c, size_t n)
+memccpy(void * __restrict t, const void * __restrict f, int c, size_t n)
 {
 
 	if (n) {