--- linux-2.6/net/ipv4/tcp_output.c.orig	2004-10-22 07:56:45.000000000 +1000
+++ linux-2.6/net/ipv4/tcp_output.c	2004-10-23 07:48:15.000000000 +1000
@@ -588,7 +588,8 @@
 	/* Any change of skb->len requires recalculation of tso
 	 * factor and mss.
 	 */
-	tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb));
+	if (tcp_skb_mss(skb))
+		tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb));
 
 	return 0;
 }