diff --git a/usr.bin/cmp/special.c b/usr.bin/cmp/special.c
index 7514c01bd59a..1342f2a86270 100644
--- a/usr.bin/cmp/special.c
+++ b/usr.bin/cmp/special.c
@@ -1,128 +1,130 @@
 /*-
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 1991, 1993, 1994
  *	The Regents of the University of California.  All rights reserved.
  *
  * 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 0
 #ifndef lint
 static char sccsid[] = "@(#)special.c	8.3 (Berkeley) 4/2/94";
 #endif
 #endif
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 
 #include <capsicum_helpers.h>
 #include <err.h>
 #include <stdlib.h>
 #include <stdio.h>
 
 #include "extern.h"
 
 void
 c_special(int fd1, const char *file1, off_t skip1,
     int fd2, const char *file2, off_t skip2, off_t limit)
 {
 	int ch1, ch2;
 	off_t byte, line;
 	FILE *fp1, *fp2;
 	int dfound;
 
 	if (caph_limit_stream(fd1, CAPH_READ) < 0)
 		err(ERR_EXIT, "caph_limit_stream(%s)", file1);
 	if (caph_limit_stream(fd2, CAPH_READ) < 0)
 		err(ERR_EXIT, "caph_limit_stream(%s)", file2);
 	if (caph_enter() < 0)
 		err(ERR_EXIT, "unable to enter capability mode");
 
 	if ((fp1 = fdopen(fd1, "r")) == NULL)
 		err(ERR_EXIT, "%s", file1);
+	(void)setvbuf(fp1, NULL, _IOFBF, 65536);
 	if ((fp2 = fdopen(fd2, "r")) == NULL)
 		err(ERR_EXIT, "%s", file2);
+	(void)setvbuf(fp2, NULL, _IOFBF, 65536);
 
 	dfound = 0;
 	while (skip1--)
 		if (getc(fp1) == EOF)
 			goto eof;
 	while (skip2--)
 		if (getc(fp2) == EOF)
 			goto eof;
 
 	for (byte = line = 1; limit == 0 || byte <= limit; ++byte) {
 #ifdef SIGINFO
 		if (info) {
 			(void)fprintf(stderr, "%s %s char %zu line %zu\n",
 			    file1, file2, (size_t)byte, (size_t)line);
 			info = 0;
 		}
 #endif
 		ch1 = getc(fp1);
 		ch2 = getc(fp2);
 		if (ch1 == EOF || ch2 == EOF)
 			break;
 		if (ch1 != ch2) {
 			if (xflag) {
 				dfound = 1;
 				(void)printf("%08llx %02x %02x\n",
 				    (long long)byte - 1, ch1, ch2);
 			} else if (lflag) {
 				dfound = 1;
 				if (bflag)
 					(void)printf("%6lld %3o %c %3o %c\n",
 					    (long long)byte, ch1, ch1, ch2,
 					    ch2);
 				else
 					(void)printf("%6lld %3o %3o\n",
 					    (long long)byte, ch1, ch2);
 			} else {
 				diffmsg(file1, file2, byte, line, ch1, ch2);
 				/* NOTREACHED */
 			}
 		}
 		if (ch1 == '\n')
 			++line;
 	}
 
 eof:	if (ferror(fp1))
 		err(ERR_EXIT, "%s", file1);
 	if (ferror(fp2))
 		err(ERR_EXIT, "%s", file2);
 	if (feof(fp1)) {
 		if (!feof(fp2))
 			eofmsg(file1);
 	} else
 		if (feof(fp2))
 			eofmsg(file2);
 	fclose(fp2);
 	fclose(fp1);
 	if (dfound)
 		exit(DIFF_EXIT);
 }