diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 4e87614313c0..0ff2f620f8e4 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2698,12 +2698,15 @@ static void tcp_mtup_probe_success(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct inet_connection_sock *icsk = inet_csk(sk);
+	u64 val;
 
-	/* FIXME: breaks with very large cwnd */
 	tp->prior_ssthresh = tcp_current_ssthresh(sk);
-	tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) *
-			     tcp_mss_to_mtu(sk, tp->mss_cache) /
-			     icsk->icsk_mtup.probe_size);
+
+	val = (u64)tcp_snd_cwnd(tp) * tcp_mss_to_mtu(sk, tp->mss_cache);
+	do_div(val, icsk->icsk_mtup.probe_size);
+	WARN_ON_ONCE((u32)val != val);
+	tcp_snd_cwnd_set(tp, max_t(u32, 1U, val));
+
 	tp->snd_cwnd_cnt = 0;
 	tp->snd_cwnd_stamp = tcp_jiffies32;
 	tp->snd_ssthresh = tcp_current_ssthresh(sk);