diff --git a/sys/net/rtsock.c b/sys/net/rtsock.c
--- a/sys/net/rtsock.c
+++ b/sys/net/rtsock.c
@@ -154,6 +154,10 @@
  * notification to a socket bound to a particular FIB.
  */
 #define	RTS_FILTER_FIB	M_PROTO8
+/*
+ * Used to store address family of the notification.
+ */
+#define	m_rtsock_family	m_pkthdr.PH_loc.eight[0]
 
 typedef struct {
 	int	ip_count;	/* attached w/ AF_INET */
@@ -292,17 +296,9 @@
 rts_input(struct mbuf *m)
 {
 	struct sockproto route_proto;
-	unsigned short *family;
-	struct m_tag *tag;
 
 	route_proto.sp_family = PF_ROUTE;
-	tag = m_tag_find(m, PACKET_TAG_RTSOCKFAM, NULL);
-	if (tag != NULL) {
-		family = (unsigned short *)(tag + 1);
-		route_proto.sp_protocol = *family;
-		m_tag_delete(m, tag);
-	} else
-		route_proto.sp_protocol = 0;
+	route_proto.sp_protocol = m->m_rtsock_family;
 
 	raw_input_ext(m, &route_proto, &route_src, raw_input_rts_cb);
 }
@@ -2183,23 +2179,10 @@
 static void
 rt_dispatch(struct mbuf *m, sa_family_t saf)
 {
-	struct m_tag *tag;
 
-	/*
-	 * Preserve the family from the sockaddr, if any, in an m_tag for
-	 * use when injecting the mbuf into the routing socket buffer from
-	 * the netisr.
-	 */
-	if (saf != AF_UNSPEC) {
-		tag = m_tag_get(PACKET_TAG_RTSOCKFAM, sizeof(unsigned short),
-		    M_NOWAIT);
-		if (tag == NULL) {
-			m_freem(m);
-			return;
-		}
-		*(unsigned short *)(tag + 1) = saf;
-		m_tag_prepend(m, tag);
-	}
+	M_ASSERTPKTHDR(m);
+
+	m->m_rtsock_family = saf;
 	if (V_loif)
 		m->m_pkthdr.rcvif = V_loif;
 	else {
diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -1385,7 +1385,7 @@
 #define	PACKET_TAG_IPFORWARD			18 /* ipforward info */
 #define	PACKET_TAG_MACLABEL	(19 | MTAG_PERSISTENT) /* MAC label */
 #define	PACKET_TAG_PF				21 /* PF/ALTQ information */
-#define	PACKET_TAG_RTSOCKFAM			25 /* rtsock sa family */
+/* was	PACKET_TAG_RTSOCKFAM			25    rtsock sa family */
 #define	PACKET_TAG_IPOPTIONS			27 /* Saved IP options */
 #define	PACKET_TAG_CARP				28 /* CARP info */
 #define	PACKET_TAG_IPSEC_NAT_T_PORTS		29 /* two uint16_t */