diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
index 7c1c57aa28..2ddafcb53c 100644
--- a/drivers/serial/serial.c
+++ b/drivers/serial/serial.c
@@ -431,8 +431,7 @@ static int uart_tcdrain(FAR uart_dev_t *dev, clock_t timeout)
 
       if (dev->disconnected)
         {
-          dev->xmit.head = 0;  /* Drop the buffered TX data */
-          dev->xmit.tail = 0;
+          dev->xmit.tail = dev->xmit.head;  /* Drop the buffered TX data */
           ret = -ENOTCONN;
         }
       else
@@ -908,17 +907,11 @@ static ssize_t uart_read(FAR struct file *filep, FAR char *buffer, size_t buflen
               flags = enter_critical_section();
 
 #ifdef CONFIG_SERIAL_DMA
-              /* If RX buffer is empty move tail and head to zero position */
-
-              if (rxbuf->head == rxbuf->tail)
-                {
-                  rxbuf->head = rxbuf->tail = 0;
-                }
-
               /* Notify DMA that there is free space in the RX buffer */
 
               uart_dmarxfree(dev);
 #endif
+              /* Re-enable UART Rx interrupts */
 
               uart_enablerxint(dev);
 
@@ -992,25 +985,16 @@ static ssize_t uart_read(FAR struct file *filep, FAR char *buffer, size_t buflen
     }
 
 #ifdef CONFIG_SERIAL_DMA
-  flags = enter_critical_section();
-
-  /* If RX buffer is empty move tail and head to zero position */
-
-  if (rxbuf->head == rxbuf->tail)
-    {
-      rxbuf->head = rxbuf->tail = 0;
-    }
-
-  leave_critical_section(flags);
-
   /* Notify DMA that there is free space in the RX buffer */
 
+  flags = enter_critical_section();
   uart_dmarxfree(dev);
+  leave_critical_section(flags);
+#endif
 
   /* RX interrupt could be disabled by RX buffer overflow. Enable it now. */
 
   uart_enablerxint(dev);
-#endif
 
 #ifdef CONFIG_SERIAL_IFLOWCONTROL
 #ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
@@ -1340,8 +1324,7 @@ static int uart_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 
               if (arg == TCIFLUSH || arg == TCIOFLUSH)
                 {
-                  dev->recv.head = 0;
-                  dev->recv.tail = 0;
+                  dev->recv.tail = dev->recv.head;
 
 #ifdef CONFIG_SERIAL_IFLOWCONTROL
                   /* De-activate RX flow control. */
@@ -1352,8 +1335,7 @@ static int uart_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 
               if (arg == TCOFLUSH || arg == TCIOFLUSH)
                 {
-                  dev->xmit.head = 0;
-                  dev->xmit.tail = 0;
+                  dev->xmit.tail = dev->xmit.head;
 
                   /* Inform any waiters there there is space available. */
 
diff --git a/drivers/serial/serial_dma.c b/drivers/serial/serial_dma.c
index 1238182bb8..17d6f6a56a 100644
--- a/drivers/serial/serial_dma.c
+++ b/drivers/serial/serial_dma.c
@@ -199,8 +199,21 @@ void uart_recvchars_dma(FAR uart_dev_t *dev)
   unsigned int watermark;
 #endif
   bool is_full;
-  int nexthead = rxbuf->head + 1;
+  int nexthead;
 
+  /* If RX buffer is empty move tail and head to zero position */
+
+  if (rxbuf->head == rxbuf->tail)
+    {
+      rxbuf->head = 0;
+      rxbuf->head = 0;
+    }
+
+  /* Get the next head index and check if there is room to adding another
+   * byte to the buffer.
+   */
+
+  nexthead = rxbuf->head + 1;
   if (nexthead >= rxbuf->size)
     {
       nexthead = 0;