diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 7c07ebb37b1b..1733f03a7da7 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1620,6 +1620,18 @@ static inline void start_tx_rs485(struct uart_port *port)
 	struct uart_8250_port *up = up_to_u8250p(port);
 	struct uart_8250_em485 *em485 = up->em485;
 
+	/*
+	 * While serial8250_em485_handle_stop_tx() is a noop if
+	 * em485->active_timer != &em485->stop_tx_timer, it might happen that
+	 * the timer is still armed and triggers only after the current bunch of
+	 * chars is send and em485->active_timer == &em485->stop_tx_timer again.
+	 * So cancel the timer. There is still a theoretical race condition if
+	 * the timer is already running and only comes around to check for
+	 * em485->active_timer when &em485->stop_tx_timer is armed again.
+	 */
+	if (em485->active_timer == &em485->stop_tx_timer)
+		hrtimer_try_to_cancel(&em485->stop_tx_timer);
+
 	em485->active_timer = NULL;
 
 	if (em485->tx_stopped) {