diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index aa08a7a5f6ac..dda3c025452e 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1613,13 +1613,6 @@ static inline int xfrm_user_policy(struct sock *sk, int optname, u8 __user *optv
 {
  	return -ENOPROTOOPT;
 }
-
-static inline int xfrm4_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
-{
- 	/* should not happen */
- 	kfree_skb(skb);
-	return 0;
-}
 #endif
 
 struct dst_entry *__xfrm_dst_lookup(struct net *net, int tos, int oif,
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index cf755156a684..f1c514cb4e87 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2520,9 +2520,11 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
 	case UDP_ENCAP:
 		switch (val) {
 		case 0:
+#ifdef CONFIG_XFRM
 		case UDP_ENCAP_ESPINUDP:
 		case UDP_ENCAP_ESPINUDP_NON_IKE:
 			up->encap_rcv = xfrm4_udp_encap_rcv;
+#endif
 			/* FALLTHROUGH */
 		case UDP_ENCAP_L2TPINUDP:
 			up->encap_type = val;