diff -uNpr linux-2.6.19.org/net/ipv4/netfilter/ip_nat_standalone.c linux-2.6.19/net/ipv4/netfilter/ip_nat_standalone.c
--- linux-2.6.19.org/net/ipv4/netfilter/ip_nat_standalone.c	2006-11-29 22:57:37.000000000 +0100
+++ linux-2.6.19/net/ipv4/netfilter/ip_nat_standalone.c	2007-03-15 08:25:11.000000000 +0100
@@ -191,11 +191,13 @@ ip_nat_in(unsigned int hooknum,
           int (*okfn)(struct sk_buff *))
 {
 	unsigned int ret;
+	__be32 saddr = (*pskb)->nh.iph->saddr;
 	__be32 daddr = (*pskb)->nh.iph->daddr;
 
 	ret = ip_nat_fn(hooknum, pskb, in, out, okfn);
 	if (ret != NF_DROP && ret != NF_STOLEN
-	    && daddr != (*pskb)->nh.iph->daddr) {
+	    && ((*pskb)->nh.iph->saddr != saddr
+	        || (*pskb)->nh.iph->daddr != daddr)) {
 		dst_release((*pskb)->dst);
 		(*pskb)->dst = NULL;
 	}