diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index c6b9f92..c072f88 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -333,6 +333,8 @@
 
 	struct tcp_sack_block_wire recv_sack_cache[4];
 
+	u32	highest_sack;	/* Start seq of globally highest revd SACK (valid only in slowpath) */
+
 	/* from STCP, retrans queue hinting */
 	struct sk_buff* lost_skb_hint;