1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/serial/m32r_sio.c b/drivers/serial/m32r_sio.c
index 348ee2c19b58..c2bb11c02bde 100644
--- a/drivers/serial/m32r_sio.c
+++ b/drivers/serial/m32r_sio.c
@@ -421,7 +421,7 @@ static void transmit_chars(struct uart_sio_port *up)
                 up->port.icount.tx++;
                 if (uart_circ_empty(xmit))
                         break;
-                while (!serial_in(up, UART_LSR) & UART_LSR_THRE);
+                while (!(serial_in(up, UART_LSR) & UART_LSR_THRE));
 
         } while (--count > 0);