diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 509eee5..6297eaf 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6316,6 +6316,7 @@ struct bpf_sk_lookup {
 	__u32 local_ip4;	/* Network byte order */
 	__u32 local_ip6[4];	/* Network byte order */
 	__u32 local_port;	/* Host byte order */
+	__u32 ingress_ifindex;		/* The arriving interface. Determined by inet_iif. */
 };
 
 /*