diff --git a/usr.sbin/mtree/Makefile b/usr.sbin/mtree/Makefile
index 5b5e03d8b416..e8afa08bd581 100644
--- a/usr.sbin/mtree/Makefile
+++ b/usr.sbin/mtree/Makefile
@@ -7,6 +7,8 @@ PROG=	mtree
 MAN=	mtree.8
 SRCS=	compare.c crc.c create.c excludes.c misc.c mtree.c spec.c verify.c
 
+WARNS?=	4
+
 .if defined(BOOTSTRAPPING)
 .PATH: ${.CURDIR}/../../lib/libc/gen
 SRCS+=	strtofflags.c
diff --git a/usr.sbin/mtree/compare.c b/usr.sbin/mtree/compare.c
index b2328a6643fa..5393b5d1c66b 100644
--- a/usr.sbin/mtree/compare.c
+++ b/usr.sbin/mtree/compare.c
@@ -63,7 +63,7 @@ static const char rcsid[] =
 extern int uflag;
 extern int lineno;
 
-static char *ftype(u_int);
+static const char *ftype(u_int);
 
 #define	INDENTNAMELEN	8
 #define	LABEL \
@@ -74,14 +74,15 @@ static char *ftype(u_int);
 
 int
 compare(name, s, p)
-	char *name;
+	char *name __unused;
 	register NODE *s;
 	register FTSENT *p;
 {
 	extern int uflag;
 	u_long len, val;
 	int fd, label;
-	char *cp, *tab = "";
+	char *cp;
+	const char *tab = "";
 	char *fflags;
 
 	label = 0;
@@ -304,7 +305,7 @@ typeerr:		LABEL;
 	return (label);
 }
 
-char *
+const char *
 inotype(type)
 	u_int type;
 {
@@ -329,7 +330,7 @@ inotype(type)
 	/* NOTREACHED */
 }
 
-static char *
+static const char *
 ftype(type)
 	u_int type;
 {
diff --git a/usr.sbin/mtree/create.c b/usr.sbin/mtree/create.c
index a7dfc67f9c72..3db05027bf9d 100644
--- a/usr.sbin/mtree/create.c
+++ b/usr.sbin/mtree/create.c
@@ -89,17 +89,18 @@ cwalk()
 {
 	register FTS *t;
 	register FTSENT *p;
-	time_t clock;
+	time_t cl;
 	char *argv[2], host[MAXHOSTNAMELEN];
+	char dot[] = ".";
 	int indent = 0;
 
-	(void)time(&clock);
+	(void)time(&cl);
 	(void)gethostname(host, sizeof(host));
 	(void)printf(
 	    "#\t   user: %s\n#\tmachine: %s\n#\t   tree: %s\n#\t   date: %s",
-	    getlogin(), host, fullpath, ctime(&clock));
+	    getlogin(), host, fullpath, ctime(&cl));
 
-	argv[0] = ".";
+	argv[0] = dot;
 	argv[1] = NULL;
 	if ((t = fts_open(argv, ftsoptions, dsort)) == NULL)
 		err(1, "line %d: fts_open", lineno);
@@ -208,7 +209,7 @@ statf(indent, p)
 		output(indent, &offset, "size=%qd", p->fts_statp->st_size);
 	if (keys & F_TIME)
 		output(indent, &offset, "time=%ld.%ld",
-		    p->fts_statp->st_mtimespec.tv_sec,
+		    (long)p->fts_statp->st_mtimespec.tv_sec,
 		    p->fts_statp->st_mtimespec.tv_nsec);
 	if (keys & F_CKSUM && S_ISREG(p->fts_statp->st_mode)) {
 		if ((fd = open(p->fts_accpath, O_RDONLY, 0)) < 0 ||
diff --git a/usr.sbin/mtree/excludes.c b/usr.sbin/mtree/excludes.c
index 624b57a9ba92..253ef00211ac 100644
--- a/usr.sbin/mtree/excludes.c
+++ b/usr.sbin/mtree/excludes.c
@@ -103,7 +103,7 @@ check_excludes(const char *fname, const char *path)
 #define MATCH(g, n) (fnmatch((g), (n), FNM_PATHNAME) == 0)
 
 	LIST_FOREACH(e, &excludes, link) {
-		if (e->pathname && MATCH(e->glob, path) 
+		if ((e->pathname && MATCH(e->glob, path)) 
 		    || MATCH(e->glob, fname))
 			return 1;
 	}
diff --git a/usr.sbin/mtree/extern.h b/usr.sbin/mtree/extern.h
index 08054305e91f..68c13aa4180a 100644
--- a/usr.sbin/mtree/extern.h
+++ b/usr.sbin/mtree/extern.h
@@ -39,7 +39,7 @@ int	 crc(int, u_long *, u_long *);
 void	 cwalk(void);
 char	*flags_to_string(u_long);
 
-char	*inotype(u_int);
+const char	*inotype(u_int);
 u_int	 parsekey(char *, int *);
 char	*rlink(char *);
 NODE	*spec(void);
diff --git a/usr.sbin/mtree/misc.c b/usr.sbin/mtree/misc.c
index 151a28bbda80..473adb7f0c52 100644
--- a/usr.sbin/mtree/misc.c
+++ b/usr.sbin/mtree/misc.c
@@ -51,7 +51,7 @@ static const char rcsid[] =
 extern int lineno;
 
 typedef struct _key {
-	char *name;			/* key name */
+	const char *name;			/* key name */
 	u_int val;			/* value */
 
 #define	NEEDVALUE	0x01
@@ -85,13 +85,14 @@ static KEY keylist[] = {
 	{"uname",	F_UNAME,	NEEDVALUE},
 };
 
+int keycompare(const void *, const void *);
+
 u_int
 parsekey(name, needvaluep)
 	char *name;
 	int *needvaluep;
 {
 	KEY *k, tmp;
-	int keycompare(const void *, const void *);
 
 	tmp.name = name;
 	k = (KEY *)bsearch(&tmp, keylist, sizeof(keylist) / sizeof(KEY),
@@ -108,7 +109,7 @@ int
 keycompare(a, b)
 	const void *a, *b;
 {
-	return (strcmp(((KEY *)a)->name, ((KEY *)b)->name));
+	return (strcmp(((const KEY *)a)->name, ((const KEY *)b)->name));
 }
 
 char *
diff --git a/usr.sbin/mtree/mtree.c b/usr.sbin/mtree/mtree.c
index 254c1b602bf3..c2c4710098a4 100644
--- a/usr.sbin/mtree/mtree.c
+++ b/usr.sbin/mtree/mtree.c
@@ -65,9 +65,7 @@ char fullpath[MAXPATHLEN];
 static void usage(void);
 
 int
-main(argc, argv)
-	int argc;
-	char *argv[];
+main(int argc, char *argv[])
 {
 	int ch;
 	char *dir, *p;
diff --git a/usr.sbin/mtree/verify.c b/usr.sbin/mtree/verify.c
index 1177f7895b88..d56ee8fdfc8a 100644
--- a/usr.sbin/mtree/verify.c
+++ b/usr.sbin/mtree/verify.c
@@ -82,8 +82,9 @@ vwalk()
 	register NODE *ep, *level;
 	int specdepth, rval;
 	char *argv[2];
+	char dot[] = ".";
 
-	argv[0] = ".";
+	argv[0] = dot;
 	argv[1] = NULL;
 	if ((t = fts_open(argv, ftsoptions, NULL)) == NULL)
 		err(1, "line %d: fts_open", lineno);