diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index bfc17c5..ef16377 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -319,7 +319,7 @@
    8 bytes of packet payload. It means, that precise relaying of
    ICMP in the real Internet is absolutely infeasible.
  */
-	struct iphdr *iph = (struct iphdr *)skb->data;
+	const struct iphdr *iph = (const struct iphdr *)skb->data;
 	const int type = icmp_hdr(skb)->type;
 	const int code = icmp_hdr(skb)->code;
 	struct ip_tunnel *t;
@@ -433,12 +433,12 @@
 {
 	struct ip_tunnel *tunnel = netdev_priv(dev);
 	struct pcpu_tstats *tstats;
-	struct iphdr  *tiph = &tunnel->parms.iph;
+	const struct iphdr  *tiph = &tunnel->parms.iph;
 	u8     tos = tunnel->parms.iph.tos;
 	__be16 df = tiph->frag_off;
 	struct rtable *rt;     			/* Route to the other host */
 	struct net_device *tdev;		/* Device to other host */
-	struct iphdr  *old_iph = ip_hdr(skb);
+	const struct iphdr  *old_iph = ip_hdr(skb);
 	struct iphdr  *iph;			/* Our new IP header */
 	unsigned int max_headroom;		/* The extra header space needed */
 	__be32 dst = tiph->daddr;
@@ -572,7 +572,7 @@
 {
 	struct net_device *tdev = NULL;
 	struct ip_tunnel *tunnel;
-	struct iphdr *iph;
+	const struct iphdr *iph;
 
 	tunnel = netdev_priv(dev);
 	iph = &tunnel->parms.iph;