diff --git a/arch/arm/src/stm32/stm32_hciuart.c b/arch/arm/src/stm32/stm32_hciuart.c
index f27e367cfd6..d8ae5c9b06a 100644
--- a/arch/arm/src/stm32/stm32_hciuart.c
+++ b/arch/arm/src/stm32/stm32_hciuart.c
@@ -1154,7 +1154,7 @@ static ssize_t hciuart_copytorxbuffer(const struct hciuart_config_s *config)
       nxsem_post(&state->rxwait);
     }
 
-  wlinfo("nbytes %ld\n", (long)nbytes);
+  wlinfo("rxhead %u rxtail %u nbytes %ld\n", rxhead, rxtail, (long)nbytes);
   return nbytes;
 }
 
@@ -1171,7 +1171,7 @@ static ssize_t hciuart_copyfromrxbuffer(const struct hciuart_config_s *config,
                                         uint8_t *dest, size_t destlen)
 {
   struct hciuart_state_s *state;
-  ssize_t nbytes = 0;
+  ssize_t nbytes;
   uint16_t rxhead;
   uint16_t rxtail;
   uint8_t rxbyte;
@@ -1181,20 +1181,14 @@ static ssize_t hciuart_copyfromrxbuffer(const struct hciuart_config_s *config,
   state  = config->state;
   rxhead = state->rxhead;
   rxtail = state->rxtail;
+  nbytes = 0;
 
-  /* Is there data available in the Rx FIFO? */
+  /* Is there data available in the Rx buffer?  Is there space in the user
+   * buffer?
+   */
 
-  while ((hciuart_getreg32(config, STM32_USART_SR_OFFSET) & USART_SR_RXNE) != 0)
+  while (rxhead != rxtail && nbytes < destlen)
     {
-      /* Is the Rx buffer empty? Is there space in the user buffer? */
-
-      if (rxhead == rxtail && nbytes < destlen)
-        {
-          /* Yes, stop the copy and update the indices */
-
-          break;
-        }
-
       /* Get a byte from the head of the Rx buffer */
 
       rxbyte = config->rxbuffer[rxhead];
@@ -1202,6 +1196,9 @@ static ssize_t hciuart_copyfromrxbuffer(const struct hciuart_config_s *config,
       /* And add it to the caller's buffer buffer */
 
       dest[nbytes] = rxbyte;
+
+      /* Update indices and counts */
+
       nbytes++;
 
       if (++rxhead >= config->rxbufsize)
@@ -1218,7 +1215,7 @@ static ssize_t hciuart_copyfromrxbuffer(const struct hciuart_config_s *config,
 
   state->rxhead = rxhead;
 
-  wlinfo("nbytes %ld\n", (long)nbytes);
+  wlinfo("rxhead %u rxtail %u nbytes %ld\n", rxhead, rxtail, (long)nbytes);
   return nbytes;
 }
 
diff --git a/configs/stm32f4discovery/hciuart/defconfig b/configs/stm32f4discovery/hciuart/defconfig
index 033acfb1140..c4af81370e5 100644
--- a/configs/stm32f4discovery/hciuart/defconfig
+++ b/configs/stm32f4discovery/hciuart/defconfig
@@ -12,6 +12,7 @@ CONFIG_ARCH_BOARD="stm32f4discovery"
 CONFIG_ARCH_BUTTONS=y
 CONFIG_ARCH_CHIP_STM32=y
 CONFIG_ARCH_CHIP_STM32F407VG=y
+CONFIG_ARCH_INTERRUPTSTACK=2048
 CONFIG_ARCH_STACKDUMP=y
 CONFIG_ARCH="arm"
 CONFIG_ARMV7M_TOOLCHAIN_CODESOURCERYW=y
@@ -65,7 +66,6 @@ CONFIG_RAM_SIZE=114688
 CONFIG_RAM_START=0x20000000
 CONFIG_RAW_BINARY=y
 CONFIG_RR_INTERVAL=200
-CONFIG_SCHED_HPWORK=y
 CONFIG_SCHED_HPWORKPRIORITY=192
 CONFIG_SCHED_WAITPID=y
 CONFIG_SDCLONE_DISABLE=y
diff --git a/drivers/wireless/bluetooth/bt_uart.c b/drivers/wireless/bluetooth/bt_uart.c
index b6f37a51ca6..1d9c203223c 100644
--- a/drivers/wireless/bluetooth/bt_uart.c
+++ b/drivers/wireless/bluetooth/bt_uart.c
@@ -212,6 +212,7 @@ static FAR struct bt_buf_s *btuart_acl_recv(FAR struct btuart_upperhalf_s *upper
 static void btuart_rxwork(FAR void *arg)
 {
   FAR struct btuart_upperhalf_s *upper;
+  FAR const struct btuart_lowerhalf_s *lower;
   static FAR struct bt_buf_s *buf;
   static unsigned int hdrlen;
   static int remaining;
@@ -219,7 +220,8 @@ static void btuart_rxwork(FAR void *arg)
   uint8_t type;
 
   upper = (FAR struct btuart_upperhalf_s *)arg;
-  DEBUGASSERT(upper != NULL);
+  DEBUGASSERT(upper != NULL && upper->lower != NULL);
+  lower = upper->lower;
 
   /* Beginning of a new packet.  Read the first byte to get the packet type. */
 
@@ -251,8 +253,7 @@ static void btuart_rxwork(FAR void *arg)
 
   if (buf == NULL)
     {
-      FAR const struct btuart_lowerhalf_s *lower = upper->lower;
-      DEBUGASSERT(lower != NULL);
+      /* Failed to allocate a buffer.  Drain the Rx data and fail the read. */
 
       nread = lower->rxdrain(lower);
       wlwarn("WARNING: Discarded %ld bytes\n", (long)nread);
@@ -276,9 +277,15 @@ static void btuart_rxwork(FAR void *arg)
       remaining -= nread;
     }
 
+  wlinfo("Full packet received\n");
+
+  /* Drain any un-read bytes from the Rx buffer */
+
+  nread = lower->rxdrain(lower);
+  wlwarn("WARNING: Discarded %ld bytes\n", (long)nread);
+
   /* Pass buffer to the stack */
 
-  wlinfo("Full packet received\n");
   upper->busy = false;
   bt_hci_receive(buf);
   return;