diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 64ab23ff559b..3637b20d3fa4 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -348,7 +348,8 @@ static int nf_ct_frag6_reasm(struct frag_queue *fq, struct sk_buff *skb,
 	skb_network_header(skb)[fq->nhoffset] = skb_transport_header(skb)[0];
 	memmove(skb->head + sizeof(struct frag_hdr), skb->head,
 		(skb->data - skb->head) - sizeof(struct frag_hdr));
-	skb->mac_header += sizeof(struct frag_hdr);
+	if (skb_mac_header_was_set(skb))
+		skb->mac_header += sizeof(struct frag_hdr);
 	skb->network_header += sizeof(struct frag_hdr);
 
 	skb_reset_transport_header(skb);