diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 384a93c..9877b68 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -849,7 +849,7 @@
 
 int ip6_dst_lookup(struct net *net, struct sock *sk, struct dst_entry **dst,
 		   struct flowi6 *fl6);
-struct dst_entry *ip6_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6,
+struct dst_entry *ip6_dst_lookup_flow(const struct sock *sk, struct flowi6 *fl6,
 				      const struct in6_addr *final_dst);
 struct dst_entry *ip6_sk_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6,
 					 const struct in6_addr *final_dst);
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 291a07b..6b0d86f 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -883,7 +883,7 @@
 	return dst;
 }
 
-static int ip6_dst_lookup_tail(struct net *net, struct sock *sk,
+static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk,
 			       struct dst_entry **dst, struct flowi6 *fl6)
 {
 #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
@@ -1014,7 +1014,7 @@
  *	It returns a valid dst pointer on success, or a pointer encoded
  *	error code.
  */
-struct dst_entry *ip6_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6,
+struct dst_entry *ip6_dst_lookup_flow(const struct sock *sk, struct flowi6 *fl6,
 				      const struct in6_addr *final_dst)
 {
 	struct dst_entry *dst = NULL;