diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 0e6ef24419c8..28edbaf7bb32 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -690,8 +690,9 @@ static void stm32_usart_transmit_chars(struct uart_port *port)
 	int ret;
 
 	if (!stm32_port->hw_flow_control &&
-	    port->rs485.flags & SER_RS485_ENABLED) {
-		stm32_port->txdone = false;
+	    port->rs485.flags & SER_RS485_ENABLED &&
+	    (port->x_char ||
+	     !(uart_circ_empty(xmit) || uart_tx_stopped(port)))) {
 		stm32_usart_tc_interrupt_disable(port);
 		stm32_usart_rs485_rts_enable(port);
 	}