diff --git a/libraries/AP_HAL_PX4/HAL_PX4_Class.cpp b/libraries/AP_HAL_PX4/HAL_PX4_Class.cpp
index ace97104ce..afbd74eca9 100644
--- a/libraries/AP_HAL_PX4/HAL_PX4_Class.cpp
+++ b/libraries/AP_HAL_PX4/HAL_PX4_Class.cpp
@@ -58,7 +58,7 @@ static PX4::SPIDeviceManager spi_mgr_instance;
 #define UARTC_DEFAULT_DEVICE "/dev/ttyS1"
 #define UARTD_DEFAULT_DEVICE "/dev/ttyS2"
 #define UARTE_DEFAULT_DEVICE "/dev/ttyS6"
-#define UARTF_DEFAULT_DEVICE "/dev/null"
+#define UARTF_DEFAULT_DEVICE "/dev/ttyS5"
 #elif defined(CONFIG_ARCH_BOARD_PX4FMU_V4) || defined(CONFIG_ARCH_BOARD_PX4FMU_V4PRO)
 #define UARTA_DEFAULT_DEVICE "/dev/ttyACM0"
 #define UARTB_DEFAULT_DEVICE "/dev/ttyS3"