diff --git a/sys/netinet/ip_output.c b/sys/netinet/ip_output.c
index 81fc061ee31d..3c61a8624488 100644
--- a/sys/netinet/ip_output.c
+++ b/sys/netinet/ip_output.c
@@ -788,7 +788,8 @@ passout:
 		 * them, there is no way for one to update all its
 		 * routes when the MTU is changed.
 		 */
-		if ((ro->ro_rt->rt_flags & (RTF_UP | RTF_HOST)) &&
+		if (ro != NULL &&
+		    (ro->ro_rt->rt_flags & (RTF_UP | RTF_HOST)) &&
 		    (ro->ro_rt->rt_rmx.rmx_mtu > ifp->if_mtu)) {
 			ro->ro_rt->rt_rmx.rmx_mtu = ifp->if_mtu;
 		}