diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 98ecfd7..fc0c42a 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1328,7 +1328,7 @@
 	/* Do software UFO. Complete and fill in the UDP checksum as HW cannot
 	 * do checksum of UDP packets sent as multiple IP fragments.
 	 */
-	offset = skb->csum_start - skb_headroom(skb);
+	offset = skb_checksum_start_offset(skb);
 	csum = skb_checksum(skb, offset, skb->len- offset, 0);
 	offset += skb->csum_offset;
 	*(__sum16 *)(skb->data + offset) = csum_fold(csum);