diff --git a/net/netfilter/nf_nat_sip.c b/net/netfilter/nf_nat_sip.c
index aea02f6aff09..762d7e7bb7c7 100644
--- a/net/netfilter/nf_nat_sip.c
+++ b/net/netfilter/nf_nat_sip.c
@@ -273,12 +273,17 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,
 				       SIP_HDR_CONTACT, &in_header,
 				       &matchoff, &matchlen,
 				       &addr, &port) > 0) {
+		int old_len = skb->len, delta;
+
 		if (!map_addr(skb, protoff, dataoff, dptr, datalen,
 			      matchoff, matchlen,
 			      &addr, port)) {
 			nf_ct_helper_log(skb, ct, "cannot mangle contact");
 			return NF_DROP;
 		}
+
+		delta = (int)skb->len - old_len;
+		coff += delta;
 	}
 
 	if (!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_FROM) ||