diff --git a/sys/netinet/tcp_output.c b/sys/netinet/tcp_output.c
index bba043e058da..b88c3a78c0fb 100644
--- a/sys/netinet/tcp_output.c
+++ b/sys/netinet/tcp_output.c
@@ -696,6 +696,8 @@ tcp_output(struct tcpcb *tp)
 		     recwin <= (so->so_rcv.sb_hiwat / 8) ||
 		     so->so_rcv.sb_hiwat <= 8 * tp->t_maxseg))
 			goto send;
+		if (2 * adv >= (int32_t)so->so_rcv.sb_hiwat)
+			goto send;
 	}
 dontupdate: