diff --git a/sys/netinet/tcp_syncache.c b/sys/netinet/tcp_syncache.c
index a10eaa4ef62e..a91fd1eca220 100644
--- a/sys/netinet/tcp_syncache.c
+++ b/sys/netinet/tcp_syncache.c
@@ -695,6 +695,8 @@ syncache_socket(struct syncache *sc, struct socket *lso, struct mbuf *m)
 	inp->inp_inc.inc_flags = sc->sc_inc.inc_flags;
 #ifdef INET6
 	if (sc->sc_inc.inc_flags & INC_ISIPV6) {
+		inp->inp_vflag &= ~INP_IPV4;
+		inp->inp_vflag |= INP_IPV6;
 		inp->in6p_laddr = sc->sc_inc.inc6_laddr;
 	} else {
 		inp->inp_vflag &= ~INP_IPV6;