diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 95fc7e893fd2..55ed4c66f77f 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -141,6 +141,9 @@ static void uart_start(struct tty_struct *tty)
 	struct uart_port *port;
 	unsigned long flags;
 
+	if (!state)
+		return;
+
 	port = uart_port_lock(state, flags);
 	__uart_start(tty);
 	uart_port_unlock(port, flags);
@@ -717,6 +720,9 @@ static void uart_unthrottle(struct tty_struct *tty)
 	struct uart_port *port;
 	upstat_t mask = 0;
 
+	if (!state)
+		return;
+
 	port = uart_port_ref(state);
 	if (!port)
 		return;