diff --git a/include/net/gre.h b/include/net/gre.h
index 4e209708b754..ced12aa787d0 100644
--- a/include/net/gre.h
+++ b/include/net/gre.h
@@ -134,12 +134,12 @@ static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
 		if (flags & TUNNEL_CSUM &&
 		    !(skb_shinfo(skb)->gso_type &
 		      (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) {
+			skb->csum_start = skb_transport_header(skb) - skb->head;
 			*ptr = 0;
 			if (skb->ip_summed == CHECKSUM_PARTIAL) {
 				*(__sum16 *)ptr = csum_fold(lco_csum(skb));
 			} else {
 				skb->ip_summed = CHECKSUM_PARTIAL;
-				skb->csum_start = skb_transport_header(skb) - skb->head;
 				skb->csum_offset = sizeof(*greh);
 			}
 		}