diff --git a/lib/libc/string/swab.c b/lib/libc/string/swab.c
index 1a30ce813784..724ee48ea0c7 100644
--- a/lib/libc/string/swab.c
+++ b/lib/libc/string/swab.c
@@ -1,63 +1,64 @@
 /*-
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 1988, 1993
  *	The Regents of the University of California.  All rights reserved.
  *
  * This code is derived from software contributed to Berkeley by
  * Jeffrey Mogul.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
 static char sccsid[] = "@(#)swab.c	8.1 (Berkeley) 6/4/93";
 #endif /* LIBC_SCCS and not lint */
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <unistd.h>
 
 void
 swab(const void * __restrict from, void * __restrict to, ssize_t len)
 {
-	unsigned long temp;
-	int n;
-	char *fp, *tp;
+	unsigned char temp;
+	size_t n;
+	const unsigned char *fp;
+	unsigned char *tp;
 
 	if (len <= 0)
 		return;
-	n = len >> 1;
-	fp = (char *)from;
-	tp = (char *)to;
+	n  = (size_t)len >> 1;
+	fp = (const unsigned char *)from;
+	tp = (unsigned char *)to;
 #define	STEP	temp = *fp++,*tp++ = *fp++,*tp++ = temp
 	/* round to multiple of 8 */
 	for (; n & 0x7; --n)
 		STEP;
 	for (n >>= 3; n > 0; --n) {
 		STEP; STEP; STEP; STEP;
 		STEP; STEP; STEP; STEP;
 	}
 }