diff --git a/sys/netinet/tcp_debug.c b/sys/netinet/tcp_debug.c
index aaeac9dfaf62..a82943d75832 100644
--- a/sys/netinet/tcp_debug.c
+++ b/sys/netinet/tcp_debug.c
@@ -171,7 +171,7 @@ tcp_trace(short act, short ostate, struct tcpcb *tp, void *ipgen,
 		ack = th->th_ack;
 		len =
 #ifdef INET6
-		    isipv6 ? ((struct ip6_hdr *)ipgen)->ip6_plen :
+		    isipv6 ? ntohs(((struct ip6_hdr *)ipgen)->ip6_plen) :
 #endif
 		    ((struct ip *)ipgen)->ip_len;
 		if (act == TA_OUTPUT) {
diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index 1d24991b3543..f349ecc8e7c5 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -381,7 +381,7 @@ tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr)
 		ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
 			(IPV6_VERSION & IPV6_VERSION_MASK);
 		ip6->ip6_nxt = IPPROTO_TCP;
-		ip6->ip6_plen = sizeof(struct tcphdr);
+		ip6->ip6_plen = htons(sizeof(struct tcphdr));
 		ip6->ip6_src = inp->in6p_laddr;
 		ip6->ip6_dst = inp->in6p_faddr;
 	} else