diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 306ea1a560e6..e31c9b6bd8ab 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -593,10 +593,8 @@ static int uart_write(struct tty_struct *tty,
 	 * This means you called this function _after_ the port was
 	 * closed.  No cookie for you.
 	 */
-	if (!state) {
-		WARN_ON(1);
+	if (WARN_ON(!state))
 		return -EL3HLT;
-	}
 
 	port = uart_port_lock(state, flags);
 	circ = &state->xmit;
@@ -659,10 +657,8 @@ static void uart_flush_buffer(struct tty_struct *tty)
 	 * This means you called this function _after_ the port was
 	 * closed.  No cookie for you.
 	 */
-	if (!state) {
-		WARN_ON(1);
+	if (WARN_ON(!state))
 		return;
-	}
 
 	pr_debug("uart_flush_buffer(%d) called\n", tty->index);