diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index b5e8de6f7507..e3dcc5501579 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -727,6 +727,8 @@ static int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
 		if (!addresses_equal(&local, addr, addr->port))
 			continue;
 
+		if (subflow->backup != bkup)
+			msk->last_snd = NULL;
 		subflow->backup = bkup;
 		subflow->send_mp_prio = 1;
 		subflow->request_bkup = bkup;