diff --git a/net/ipv4/tcp_cdg.c b/net/ipv4/tcp_cdg.c
index 06fbe102a425f28b43294925d8d13af4a13ec776..37eebd9103961be4731323cfb4d933b51954e802 100644
--- a/net/ipv4/tcp_cdg.c
+++ b/net/ipv4/tcp_cdg.c
@@ -146,7 +146,7 @@ static void tcp_cdg_hystart_update(struct sock *sk)
 		return;
 
 	if (hystart_detect & HYSTART_ACK_TRAIN) {
-		u32 now_us = div_u64(local_clock(), NSEC_PER_USEC);
+		u32 now_us = tp->tcp_mstamp;
 
 		if (ca->last_ack == 0 || !tcp_is_cwnd_limited(sk)) {
 			ca->last_ack = now_us;