diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
index 4394a52bbb..1de8076ce3 100644
--- a/drivers/serial/serial.c
+++ b/drivers/serial/serial.c
@@ -191,10 +191,6 @@ static int uart_putxmitchar(FAR uart_dev_t *dev, int ch, bool oktoblock)
   int nexthead;
   int ret;
 
-#ifdef CONFIG_SMP
-  irqstate_t flags2 = enter_critical_section();
-#endif
-
   /* Increment to see what the next head pointer will be.
    * We need to use the "next" head pointer to determine when the circular
    *  buffer would overrun
@@ -330,10 +326,6 @@ static int uart_putxmitchar(FAR uart_dev_t *dev, int ch, bool oktoblock)
 
 err_out:
 
-#ifdef CONFIG_SMP
-  leave_critical_section(flags2);
-#endif
-
   return ret;
 }