diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
index 1f6ab0fad2ae314b23b27ea0c8dcf3740216a0d3..d63f4837cb92df5a4723adef9ac506d3e80bd4b6 100644
--- a/drivers/serial/serial.c
+++ b/drivers/serial/serial.c
@@ -1339,6 +1339,7 @@ static int uart_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
                 }
 
               leave_critical_section(flags);
+              ret = 0;
             }
             break;