diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
index 34340c9c95fa..f376b05cca81 100644
--- a/net/ipv4/tcp_cubic.c
+++ b/net/ipv4/tcp_cubic.c
@@ -93,6 +93,7 @@ struct bictcp {
 	u32	ack_cnt;	/* number of acks */
 	u32	tcp_cwnd;	/* estimated tcp cwnd */
 #define ACK_RATIO_SHIFT	4
+#define ACK_RATIO_LIMIT (32u << ACK_RATIO_SHIFT)
 	u16	delayed_ack;	/* estimate the ratio of Packets/ACKs << 4 */
 	u8	sample_cnt;	/* number of samples to decide curr_rtt */
 	u8	found;		/* the exit point is found? */
@@ -398,8 +399,12 @@ static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt_us)
 	u32 delay;
 
 	if (icsk->icsk_ca_state == TCP_CA_Open) {
-		cnt -= ca->delayed_ack >> ACK_RATIO_SHIFT;
-		ca->delayed_ack += cnt;
+		u32 ratio = ca->delayed_ack;
+
+		ratio -= ca->delayed_ack >> ACK_RATIO_SHIFT;
+		ratio += cnt;
+
+		ca->delayed_ack = min(ratio, ACK_RATIO_LIMIT);
 	}
 
 	/* Some calls are for duplicates without timetamps */