diff --git a/sys/netinet/in_pcb.c b/sys/netinet/in_pcb.c
index e8506c32385c..59aec2eaec1b 100644
--- a/sys/netinet/in_pcb.c
+++ b/sys/netinet/in_pcb.c
@@ -413,12 +413,15 @@ in_pcbladdr(inp, nam, plocal_sin)
 		/*
 		 * If route is known or can be allocated now,
 		 * our src addr is taken from the i/f, else punt.
+		 * Note that we should check the address family of the cached
+		 * destination, in case of sharing the cache with IPv6.
 		 */
 		ro = &inp->inp_route;
 		if (ro->ro_rt &&
-		    (satosin(&ro->ro_dst)->sin_addr.s_addr !=
-			sin->sin_addr.s_addr ||
-		    inp->inp_socket->so_options & SO_DONTROUTE)) {
+		    (ro->ro_dst.sa_family != AF_INET ||
+		     satosin(&ro->ro_dst)->sin_addr.s_addr !=
+		     sin->sin_addr.s_addr ||
+		     inp->inp_socket->so_options & SO_DONTROUTE)) {
 			RTFREE(ro->ro_rt);
 			ro->ro_rt = (struct rtentry *)0;
 		}
@@ -426,6 +429,7 @@ in_pcbladdr(inp, nam, plocal_sin)
 		    (ro->ro_rt == (struct rtentry *)0 ||
 		    ro->ro_rt->rt_ifp == (struct ifnet *)0)) {
 			/* No route yet, so try to acquire one */
+			bzero(&ro->ro_dst, sizeof(struct sockaddr_in));
 			ro->ro_dst.sa_family = AF_INET;
 			ro->ro_dst.sa_len = sizeof(struct sockaddr_in);
 			((struct sockaddr_in *) &ro->ro_dst)->sin_addr =
diff --git a/sys/netinet/ip_output.c b/sys/netinet/ip_output.c
index af06486163d6..1b9c28d6d60d 100644
--- a/sys/netinet/ip_output.c
+++ b/sys/netinet/ip_output.c
@@ -224,13 +224,17 @@ ip_output(m0, opt, ro, flags, imo)
 	 * If there is a cached route,
 	 * check that it is to the same destination
 	 * and is still up.  If not, free it and try again.
+	 * The address family should also be checked in case of sharing the
+	 * cache with IPv6.
 	 */
 	if (ro->ro_rt && ((ro->ro_rt->rt_flags & RTF_UP) == 0 ||
-	   dst->sin_addr.s_addr != pkt_dst.s_addr)) {
+			  dst->sin_family != AF_INET ||
+			  dst->sin_addr.s_addr != pkt_dst.s_addr)) {
 		RTFREE(ro->ro_rt);
 		ro->ro_rt = (struct rtentry *)0;
 	}
 	if (ro->ro_rt == 0) {
+		bzero(dst, sizeof(*dst));
 		dst->sin_family = AF_INET;
 		dst->sin_len = sizeof(*dst);
 		dst->sin_addr = pkt_dst;