--- /sys/src/9/ip/tcp.c	Fri Feb  7 20:12:42 2014
+++ /sys/src/9/ip/tcp.c	Thu Mar  6 02:52:18 2014
@@ -128,6 +128,7 @@
 	uchar	tcplen[2];
 	uchar	tcpsrc[4];
 	uchar	tcpdst[4];
+	/* same as v6 from here on */
 	uchar	tcpsport[2];
 	uchar	tcpdport[2];
 	uchar	tcpseq[4];
@@ -149,6 +150,7 @@
 	uchar	ttl;
 	uchar	tcpsrc[IPaddrlen];
 	uchar	tcpdst[IPaddrlen];
+	/* same as v4 from here on */
 	uchar	tcpsport[2];
 	uchar	tcpdport[2];
 	uchar	tcpseq[4];