diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index c2e73e6..ab92a36 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -40,7 +40,8 @@
 	u16 offset = sizeof(struct ipv6hdr);
 	struct ipv6_opt_hdr *exthdr =
 				(struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
-	unsigned int packet_len = skb->tail - skb->network_header;
+	unsigned int packet_len = skb_tail_pointer(skb) -
+		skb_network_header(skb);
 	int found_rhdr = 0;
 	*nexthdr = &ipv6_hdr(skb)->nexthdr;