diff --git a/sys/netinet/tcp_debug.c b/sys/netinet/tcp_debug.c
index 9cf03349af30..d84c37afe56d 100644
--- a/sys/netinet/tcp_debug.c
+++ b/sys/netinet/tcp_debug.c
@@ -53,6 +53,7 @@
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/protosw.h>
+#include <sys/socket.h>
 
 #include <netinet/in.h>
 #include <netinet/in_systm.h>
@@ -96,6 +97,11 @@ tcp_trace(act, ostate, tp, ipgen, th, req)
 #ifdef INET6
 	isipv6 = (ipgen != NULL && ((struct ip *)ipgen)->ip_v == 6) ? 1 : 0;
 #endif /* INET6 */
+	td->td_family =
+#ifdef INET6
+		(isipv6 != 0) ? AF_INET6 :
+#endif
+		AF_INET;
 	if (tcp_debx == TCP_NDEBUG)
 		tcp_debx = 0;
 	td->td_time = iptime();
@@ -106,18 +112,54 @@ tcp_trace(act, ostate, tp, ipgen, th, req)
 		td->td_cb = *tp;
 	else
 		bzero((caddr_t)&td->td_cb, sizeof (*tp));
-	if (ipgen)
-		bcopy((caddr_t)ipgen, td->td_ipgen,
+	if (ipgen) {
+		switch (td->td_family) {
+		case AF_INET:
+			bcopy((caddr_t)ipgen, (caddr_t)&td->td_ti.ti_i,
+			      sizeof(td->td_ti.ti_i));
+			bzero((caddr_t)td->td_ip6buf, sizeof(td->td_ip6buf));
+			break;
 #ifdef INET6
-		      isipv6 ? sizeof(struct ip6_hdr) :
+		case AF_INET6:
+			bcopy((caddr_t)ipgen, (caddr_t)td->td_ip6buf,
+			      sizeof(td->td_ip6buf));
+			bzero((caddr_t)&td->td_ti.ti_i,
+			      sizeof(td->td_ti.ti_i));
+			break;
 #endif
-		      sizeof(struct ip));
-	else
-		bzero((caddr_t)td->td_ipgen, sizeof (td->td_ipgen));
-	if (th)
-		td->td_th = *th;
-	else
-		bzero((caddr_t)&td->td_th, sizeof (td->td_th));
+		default:
+			bzero((caddr_t)td->td_ip6buf, sizeof(td->td_ip6buf));
+			bzero((caddr_t)&td->td_ti.ti_i,
+			      sizeof(td->td_ti.ti_i));
+			break;
+		}
+	} else {
+		bzero((caddr_t)&td->td_ti.ti_i, sizeof(td->td_ti.ti_i));
+		bzero((caddr_t)td->td_ip6buf, sizeof(td->td_ip6buf));
+	}
+	if (th) {
+		switch (td->td_family) {
+		case AF_INET:
+			td->td_ti.ti_t = *th;
+			bzero((caddr_t)&td->td_ti6.th, sizeof(td->td_ti6.th));
+			break;
+#ifdef INET6
+		case AF_INET6:
+			td->td_ti6.th = *th;
+			bzero((caddr_t)&td->td_ti.ti_t,
+			      sizeof(td->td_ti.ti_t));
+			break;
+#endif
+		default:
+			bzero((caddr_t)&td->td_ti.ti_t,
+			      sizeof(td->td_ti.ti_t));
+			bzero((caddr_t)&td->td_ti6.th, sizeof(td->td_ti6.th));
+			break;
+		}
+	} else {
+		bzero((caddr_t)&td->td_ti.ti_t, sizeof(td->td_ti.ti_t));
+		bzero((caddr_t)&td->td_ti6.th, sizeof(td->td_ti6.th));
+	}
 	td->td_req = req;
 #ifdef TCPDEBUG
 	if (tcpconsdebug == 0)
diff --git a/sys/netinet/tcp_debug.h b/sys/netinet/tcp_debug.h
index 98275392844b..773d3e4bb250 100644
--- a/sys/netinet/tcp_debug.h
+++ b/sys/netinet/tcp_debug.h
@@ -42,8 +42,21 @@ struct	tcp_debug {
 	short	td_act;
 	short	td_ostate;
 	caddr_t	td_tcb;
-	u_char	td_ipgen[40]; /* the size must be of max ip header, now IPv6 */
-	struct	tcphdr td_th;
+	int	td_family;
+	/*
+	 * Co-existense of td_ti and td_ti6 below is ugly, but it is necessary
+	 * to achieve backword compatibility to some extent.
+	 */
+	struct	tcpiphdr td_ti;
+	struct {
+#if !defined(_KERNEL) && defined(INET6)
+		struct	ip6_hdr ip6;
+#else
+		u_char	ip6buf[40]; /* sizeof(struct ip6_hdr) */
+#endif
+		struct	tcphdr th;
+	} td_ti6;
+#define	td_ip6buf	td_ti6.ip6buf
 	short	td_req;
 	struct	tcpcb td_cb;
 };
diff --git a/usr.sbin/trpt/trpt.c b/usr.sbin/trpt/trpt.c
index 66e51d84e9bc..9258af76df64 100644
--- a/usr.sbin/trpt/trpt.c
+++ b/usr.sbin/trpt/trpt.c
@@ -100,7 +100,7 @@ void dotrace __P((caddr_t));
 void klseek __P((int, off_t, int));
 int numeric __P((caddr_t *, caddr_t *));
 void tcp_trace __P((short, short, struct tcpcb *, struct tcpcb *,
-			void *, struct tcphdr *, int));
+			int, void *, struct tcphdr *, int));
 static void usage __P((void));
 
 int
@@ -227,7 +227,7 @@ dotrace(tcpcb)
 {
 	register struct tcp_debug *td;
 	register int i;
-	int prev_debx = tcp_debx;
+	int prev_debx = tcp_debx, family;
 
 again:	if (--tcp_debx < 0)
 		tcp_debx = TCP_NDEBUG - 1;
@@ -236,8 +236,27 @@ again:	if (--tcp_debx < 0)
 		if (tcpcb && td->td_tcb != tcpcb)
 			continue;
 		ntime = ntohl(td->td_time);
-		tcp_trace(td->td_act, td->td_ostate, td->td_tcb, &td->td_cb,
-		    td->td_ipgen, &td->td_th, td->td_req);
+#ifdef INET6
+		family = td->td_family;
+#else
+		family = AF_INET;
+#endif
+		switch(family) {
+		case AF_INET:
+			tcp_trace(td->td_act, td->td_ostate,
+				  (struct tcpcb *)td->td_tcb,
+				  &td->td_cb, td->td_family, &td->td_ti.ti_i,
+				  &td->td_ti.ti_t, td->td_req);
+			break;
+#ifdef INET6
+		case AF_INET6:
+			tcp_trace(td->td_act, td->td_ostate,
+				  (struct tcpcb *)td->td_tcb,
+				  &td->td_cb, td->td_family, &td->td_ti6.ip6,
+				  &td->td_ti6.th, td->td_req);
+			break;
+#endif
+		}
 		if (i == tcp_debx)
 			goto done;
 	}
@@ -246,8 +265,27 @@ again:	if (--tcp_debx < 0)
 		if (tcpcb && td->td_tcb != tcpcb)
 			continue;
 		ntime = ntohl(td->td_time);
-		tcp_trace(td->td_act, td->td_ostate, td->td_tcb, &td->td_cb,
-		    td->td_ipgen, &td->td_th, td->td_req);
+#ifdef INET6
+		family = td->td_family;
+#else
+		family = AF_INET;
+#endif
+		switch(family) {
+		case AF_INET:
+			tcp_trace(td->td_act, td->td_ostate,
+				  (struct tcpcb *)td->td_tcb,
+				  &td->td_cb, td->td_family, &td->td_ti.ti_i,
+				  &td->td_ti.ti_t, td->td_req);
+			break;
+#ifdef INET6
+		case AF_INET6:
+			tcp_trace(td->td_act, td->td_ostate,
+				  (struct tcpcb *)td->td_tcb,
+				  &td->td_cb, td->td_family, &td->td_ti6.ip6,
+				  &td->td_ti6.th, td->td_req);
+			break;
+#endif
+		}
 	}
 done:	if (follow) {
 		prev_debx = tcp_debx + 1;
@@ -273,9 +311,10 @@ done:	if (follow) {
  */
 /*ARGSUSED*/
 void
-tcp_trace(act, ostate, atp, tp, ip, th, req)
+tcp_trace(act, ostate, atp, tp, family, ip, th, req)
 	short act, ostate;
 	struct tcpcb *atp, *tp;
+	int family;
 	void *ip;
 	struct tcphdr *th;
 	int req;
@@ -290,12 +329,13 @@ tcp_trace(act, ostate, atp, tp, ip, th, req)
 #endif
 
 #ifdef INET6
-	switch (((struct ip *)ip)->ip_v) {
-	case 4:
+	switch (family) {
+	case AF_INET:
 		nopkt = 0;
+		isipv6 = 0;
 		ip4 = (struct ip *)ip;
 		break;
-	case 6:
+	case AF_INET6:
 		nopkt = 0;
 		isipv6 = 1;
 		ip6 = (struct ip6_hdr *)ip;