diff --git a/arch/arm/src/stm32/stm32_serial.c b/arch/arm/src/stm32/stm32_serial.c
index 381df6c016f..6152d5795d7 100644
--- a/arch/arm/src/stm32/stm32_serial.c
+++ b/arch/arm/src/stm32/stm32_serial.c
@@ -1189,6 +1189,13 @@ static int up_dma_nextrx(struct up_dev_s *priv)
 static void up_set_format(struct uart_dev_s *dev)
 {
   struct up_dev_s *priv = (struct up_dev_s *)dev->priv;
+#if defined(CONFIG_STM32_STM32F30XX) || defined(CONFIG_STM32_STM32F37XX)
+  uint32_t usartdiv8;
+#else
+  uint32_t usartdiv32;
+  uint32_t mantissa;
+  uint32_t fraction;
+#endif
   uint32_t regval;
   uint32_t brr;
 
@@ -1201,11 +1208,8 @@ static void up_set_format(struct uart_dev_s *dev)
    * by 8 in additional to the standard oversampling by 16.
    * With baud rate of fCK / Divider for oversampling by 16.
    * and baud rate of  2 * fCK / Divider for oversampling by 8
-   */
-
-  uint32_t usartdiv8;
-
-  /* In case of oversampling by 8, the equation is:
+   *
+   * In case of oversampling by 8, the equation is:
    *
    *   baud      = 2 * fCK / usartdiv8
    *   usartdiv8 = 2 * fCK / baud
@@ -1219,10 +1223,10 @@ static void up_set_format(struct uart_dev_s *dev)
    *   baud       = fCK / usartdiv16
    *   usartdiv16 = fCK / baud
    *              = 2 * usartdiv8
+   *
+   * Use oversamply by 8 only if the divisor is small.  But what is small?
    */
 
-  /* Use oversamply by 8 only if the divisor is small.  But what is small? */
-
   if (usartdiv8 > 100)
     {
       /* Use usartdiv16 */
@@ -1247,16 +1251,10 @@ static void up_set_format(struct uart_dev_s *dev)
     }
 
 #else
-
   /* This second implementation is for U[S]ARTs that support fractional
    * dividers.
-   */
-
-  uint32_t usartdiv32;
-  uint32_t mantissa;
-  uint32_t fraction;
-
-  /* Configure the USART Baud Rate.  The baud rate for the receiver and
+   *
+   * Configure the USART Baud Rate.  The baud rate for the receiver and
    * transmitter (Rx and Tx) are both set to the same value as programmed
    * in the Mantissa and Fraction values of USARTDIV.
    *
@@ -1283,9 +1281,9 @@ static void up_set_format(struct uart_dev_s *dev)
   fraction   = (usartdiv32 - (mantissa << 5) + 1) >> 1;
 
 #if defined(CONFIG_STM32_STM32F40XX)
-
   /* The F4 supports 8 X in oversampling additional to the
    * standard oversampling by 16.
+   *
    * With baud rate of fCK / (16 * Divider) for oversampling by 16.
    * and baud rate of  fCK /  (8 * Divider) for oversampling by 8
    */
@@ -1300,18 +1298,20 @@ static void up_set_format(struct uart_dev_s *dev)
 
       mantissa = usartdiv32 >> 4;
 
-     /* The fractional remainder (with rounding) */
+      /* The fractional remainder (with rounding) */
 
-     fraction = (usartdiv32 - (mantissa << 4) + 1) >> 1;
+      fraction = (usartdiv32 - (mantissa << 4) + 1) >> 1;
     }
   else
-    {/* Use 16x Oversampling */
+    {
+      /* Use 16x Oversampling */
+
       regval &= ~USART_CR1_OVER8;
     }
 #endif
 
-  brr        = mantissa << USART_BRR_MANT_SHIFT;
-  brr       |= fraction << USART_BRR_FRAC_SHIFT;
+  brr  = mantissa << USART_BRR_MANT_SHIFT;
+  brr |= fraction << USART_BRR_FRAC_SHIFT;
 #endif
 
   up_serialout(priv, STM32_USART_CR1_OFFSET, regval);
@@ -1364,7 +1364,8 @@ static void up_set_format(struct uart_dev_s *dev)
   regval  = up_serialin(priv, STM32_USART_CR3_OFFSET);
   regval &= ~(USART_CR3_CTSE | USART_CR3_RTSE);
 
-#if defined(CONFIG_SERIAL_IFLOWCONTROL) && !defined(CONFIG_STM32_FLOWCONTROL_BROKEN)
+#if defined(CONFIG_SERIAL_IFLOWCONTROL) && \
+   !defined(CONFIG_STM32_FLOWCONTROL_BROKEN)
   if (priv->iflow && (priv->rts_gpio != 0))
     {
       regval |= USART_CR3_RTSE;