diff --git a/arch/arm/src/stm32/stm32_serial.c b/arch/arm/src/stm32/stm32_serial.c
index 584215e5c8..ebb702ed4a 100644
--- a/arch/arm/src/stm32/stm32_serial.c
+++ b/arch/arm/src/stm32/stm32_serial.c
@@ -508,7 +508,8 @@ static bool up_rxflowcontrol(struct uart_dev_s *dev, unsigned int nbuffered,
                              bool upper);
 #endif
 static void up_send(struct uart_dev_s *dev, int ch);
-#if defined(SERIAL_HAVE_RXDMA_OPS) || defined(SERIAL_HAVE_NODMA_OPS)
+#if defined(SERIAL_HAVE_RXDMA_OPS) || defined(SERIAL_HAVE_NODMA_OPS) || \
+    defined(CONFIG_STM32_SERIALBRK_BSDCOMPAT)
 static void up_txint(struct uart_dev_s *dev, bool enable);
 #endif
 static bool up_txready(struct uart_dev_s *dev);
@@ -2919,7 +2920,8 @@ static void up_dma_txint(struct uart_dev_s *dev, bool enable)
  *
  ****************************************************************************/
 
-#if defined(SERIAL_HAVE_RXDMA_OPS) || defined(SERIAL_HAVE_NODMA_OPS)
+#if defined(SERIAL_HAVE_RXDMA_OPS) || defined(SERIAL_HAVE_NODMA_OPS) || \
+    defined(CONFIG_STM32_SERIALBRK_BSDCOMPAT)
 static void up_txint(struct uart_dev_s *dev, bool enable)
 {
   struct up_dev_s *priv = (struct up_dev_s *)dev->priv;