diff --git a/usr.bin/cmp/cmp.c b/usr.bin/cmp/cmp.c
index 73e89e4aaf7..3d1e55f85b9 100644
--- a/usr.bin/cmp/cmp.c
+++ b/usr.bin/cmp/cmp.c
@@ -68,7 +68,7 @@ main(argc, argv)
 	struct stat sb1, sb2;
 	off_t skip1, skip2;
 	int ch, fd1, fd2, special;
-	char *file1, *file2;
+	const char *file1, *file2;
 
 	while ((ch = getopt(argc, argv, "-lsxz")) != -1)
 		switch (ch) {
diff --git a/usr.bin/cmp/extern.h b/usr.bin/cmp/extern.h
index f3f25d764d6..9ab37d6d372 100644
--- a/usr.bin/cmp/extern.h
+++ b/usr.bin/cmp/extern.h
@@ -40,9 +40,9 @@
 #define DIFF_EXIT	1
 #define ERR_EXIT	2	/* error exit code */
 
-void	c_regular __P((int, char *, off_t, off_t, int, char *, off_t, off_t));
-void	c_special __P((int, char *, off_t, int, char *, off_t));
-void	diffmsg __P((char *, char *, off_t, off_t));
-void	eofmsg __P((char *));
+void	c_regular __P((int, const char *, off_t, off_t, int, const char *, off_t, off_t));
+void	c_special __P((int, const char *, off_t, int, const char *, off_t));
+void	diffmsg __P((const char *, const char *, off_t, off_t));
+void	eofmsg __P((const char *));
 
 extern int lflag, sflag, xflag;
diff --git a/usr.bin/cmp/misc.c b/usr.bin/cmp/misc.c
index 248ef93f0b7..258d8606396 100644
--- a/usr.bin/cmp/misc.c
+++ b/usr.bin/cmp/misc.c
@@ -29,6 +29,9 @@
  * 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.
+ *
+ * $FreeBSD$
+ *
  */
 
 #ifndef lint
@@ -45,7 +48,7 @@ static const char sccsid[] = "@(#)misc.c	8.3 (Berkeley) 4/2/94";
 
 void
 eofmsg(file)
-	char *file;
+	const char *file;
 {
 	if (!sflag)
 		warnx("EOF on %s", file);
@@ -54,7 +57,7 @@ eofmsg(file)
 
 void
 diffmsg(file1, file2, byte, line)
-	char *file1, *file2;
+	const char *file1, *file2;
 	off_t byte, line;
 {
 	if (!sflag)
diff --git a/usr.bin/cmp/regular.c b/usr.bin/cmp/regular.c
index ec46827d625..3c0b5ae1712 100644
--- a/usr.bin/cmp/regular.c
+++ b/usr.bin/cmp/regular.c
@@ -59,7 +59,7 @@ static u_char *remmap __P((u_char *, int, off_t));
 void
 c_regular(fd1, file1, skip1, len1, fd2, file2, skip2, len2)
 	int fd1, fd2;
-	char *file1, *file2;
+	const char *file1, *file2;
 	off_t skip1, len1, skip2, len2;
 {
 	u_char ch, *p1, *p2, *m1, *m2, *e1, *e2;
diff --git a/usr.bin/cmp/special.c b/usr.bin/cmp/special.c
index a9033b363c8..77d21bdd14e 100644
--- a/usr.bin/cmp/special.c
+++ b/usr.bin/cmp/special.c
@@ -29,6 +29,9 @@
  * 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.
+ *
+ * $FreeBSD$
+ *
  */
 
 #ifndef lint
@@ -47,7 +50,7 @@ static const char sccsid[] = "@(#)special.c	8.3 (Berkeley) 4/2/94";
 void
 c_special(fd1, file1, skip1, fd2, file2, skip2)
 	int fd1, fd2;
-	char *file1, *file2;
+	const char *file1, *file2;
 	off_t skip1, skip2;
 {
 	int ch1, ch2;