diff --git a/libraries/AP_HAL_PX4/HAL_PX4_Class.cpp b/libraries/AP_HAL_PX4/HAL_PX4_Class.cpp
index 01b05f5cdd..784ff6ecf4 100644
--- a/libraries/AP_HAL_PX4/HAL_PX4_Class.cpp
+++ b/libraries/AP_HAL_PX4/HAL_PX4_Class.cpp
@@ -45,12 +45,18 @@ static PX4GPIO gpioDriver;
 
 static Empty::I2CDeviceManager i2c_mgr_instance;
 
-#if defined(CONFIG_ARCH_BOARD_PX4FMU_V2) || defined(CONFIG_ARCH_BOARD_PX4FMU_V4)
+#if defined(CONFIG_ARCH_BOARD_PX4FMU_V2)
 #define UARTA_DEFAULT_DEVICE "/dev/ttyACM0"
 #define UARTB_DEFAULT_DEVICE "/dev/ttyS3"
 #define UARTC_DEFAULT_DEVICE "/dev/ttyS1"
 #define UARTD_DEFAULT_DEVICE "/dev/ttyS2"
 #define UARTE_DEFAULT_DEVICE "/dev/ttyS6"
+#elif defined(CONFIG_ARCH_BOARD_PX4FMU_V4)
+#define UARTA_DEFAULT_DEVICE "/dev/ttyACM0"
+#define UARTB_DEFAULT_DEVICE "/dev/ttyS3"
+#define UARTC_DEFAULT_DEVICE "/dev/ttyS1"
+#define UARTD_DEFAULT_DEVICE "/dev/ttyS2"
+#define UARTE_DEFAULT_DEVICE "/dev/ttyS0"
 #else
 #define UARTA_DEFAULT_DEVICE "/dev/ttyACM0"
 #define UARTB_DEFAULT_DEVICE "/dev/ttyS3"