diff --git a/hal/targets/hal/TARGET_STM/TARGET_STM32F4/TARGET_NUCLEO_F446ZE/objects.h b/hal/targets/hal/TARGET_STM/TARGET_STM32F4/TARGET_NUCLEO_F446ZE/objects.h
index 98a6603e5b4..dd4528b9597 100644
--- a/hal/targets/hal/TARGET_STM/TARGET_STM32F4/TARGET_NUCLEO_F446ZE/objects.h
+++ b/hal/targets/hal/TARGET_STM/TARGET_STM32F4/TARGET_NUCLEO_F446ZE/objects.h
@@ -74,6 +74,11 @@ struct serial_s {
     uint32_t parity;
     PinName pin_tx;
     PinName pin_rx;
+#if DEVICE_SERIAL_FC
+    uint32_t hw_flow_ctl;
+    PinName pin_rts;
+    PinName pin_cts;
+#endif
 };
 
 struct spi_s {