diff --git a/usr.sbin/mrouted/mapper.c b/usr.sbin/mrouted/mapper.c
index aa5aabddf8f0..3691aeaefa4b 100644
--- a/usr.sbin/mrouted/mapper.c
+++ b/usr.sbin/mrouted/mapper.c
@@ -826,7 +826,7 @@ u_int32 host_addr(name)
     struct hostent *e = gethostbyname(name);
     int addr;
 
-    if (e)
+    if (e && e->h_length == sizeof(addr))
 	memcpy(&addr, e->h_addr_list[0], e->h_length);
     else {
 	addr = inet_addr(name);
diff --git a/usr.sbin/mrouted/mrinfo.c b/usr.sbin/mrouted/mrinfo.c
index 58e5544dfb23..2467c3d5b41b 100644
--- a/usr.sbin/mrouted/mrinfo.c
+++ b/usr.sbin/mrouted/mrinfo.c
@@ -383,7 +383,7 @@ main(argc, argv)
 	} else
 		hp = gethostbyname(host);
 
-	if (hp == NULL) {
+	if (hp == NULL || hp->h_length != sizeof(target_addr)) {
 		fprintf(stderr, "mrinfo: %s: no such host\n", argv[0]);
 		exit(1);
 	}
diff --git a/usr.sbin/mrouted/mtrace.c b/usr.sbin/mrouted/mtrace.c
index 2164b91a1b7b..9ffa1852ee56 100644
--- a/usr.sbin/mrouted/mtrace.c
+++ b/usr.sbin/mrouted/mtrace.c
@@ -759,7 +759,8 @@ host_addr(name)
     *op = '\0';
 
     if (dots <= 0) e = gethostbyname(name);
-    if (e) memcpy((char *)&addr, e->h_addr_list[0], e->h_length);
+    if (e && e->h_length == sizeof(addr))
+	memcpy((char *)&addr, e->h_addr_list[0], e->h_length);
     else {
 	addr = inet_addr(buf);
 	if (addr == -1 || (IN_MULTICAST(addr) && dots)) {