diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index 5709494..724553e 100644
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -205,7 +205,7 @@
 	{
 		struct icmphdr *icmph;
 
-		if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph)))
+		if (!pskb_may_pull(skb, ihl + sizeof(*icmph)))
 			goto drop;
 
 		icmph = (void *)(skb_network_header(skb) + ihl);
@@ -215,6 +215,9 @@
 		    (icmph->type != ICMP_PARAMETERPROB))
 			break;
 
+		if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph)))
+			goto drop;
+
 		iph = (void *)(icmph + 1);
 		if (egress)
 			addr = iph->daddr;