diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 8a7fc4b..60b7aac 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -191,7 +191,8 @@
 	u8	do_early_retrans:1,/* Enable RFC5827 early-retransmit  */
 		early_retrans_delayed:1, /* Delayed ER timer installed */
 		syn_data:1,	/* SYN includes data */
-		syn_fastopen:1;	/* SYN includes Fast Open option */
+		syn_fastopen:1,	/* SYN includes Fast Open option */
+		syn_data_acked:1;/* data in SYN is acked by SYN-ACK */
 
 /* RTT measurement */
 	u32	srtt;		/* smoothed round trip time << 3	*/