diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c
index 64f1cbaf96e8..5aa5f5496d6d 100644
--- a/net/ipv4/tcp_illinois.c
+++ b/net/ipv4/tcp_illinois.c
@@ -298,7 +298,7 @@ static u32 tcp_illinois_ssthresh(struct sock *sk)
 	struct illinois *ca = inet_csk_ca(sk);
 
 	/* Multiplicative decrease */
-	return max((tp->snd_cwnd * ca->beta) >> BETA_SHIFT, 2U);
+	return max(tp->snd_cwnd - ((tp->snd_cwnd * ca->beta) >> BETA_SHIFT), 2U);
 }