diff --git a/libraries/AP_HAL_ChibiOS/hwdef/MambaH743v4/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/MambaH743v4/hwdef.dat
index 942924ad471a72..a6c13e646976ab 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/MambaH743v4/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/MambaH743v4/hwdef.dat
@@ -33,7 +33,7 @@ define HAL_LOGGING_DATAFLASH_ENABLED 1
 I2C_ORDER I2C1 I2C2
 
 # order of UARTs (and USB)
-SERIAL_ORDER OTG1 USART1 USART2 USART3 UART4 UART5 USART6 UART7 UART8
+SERIAL_ORDER OTG1 USART1 USART2 USART3 EMPTY UART5 USART6 UART7 UART8
 
 # buzzer
 PE3 BUZZER OUTPUT LOW PULLDOWN GPIO(80)
@@ -101,18 +101,15 @@ define HAL_GPIO_B_LED_PIN 90
 PA9  USART1_TX USART1
 PA10 USART1_RX USART1
 
-# USART2
-PD5 USART2_TX USART2 NODMA
-PD6 USART2_RX USART2 NODMA
+# USART2 (GPS)
+PD5 USART2_TX USART2
+PD6 USART2_RX USART2
+define DEFAULT_SERIAL2_PROTOCOL SerialProtocol_GPS
 
 # USART3 (VTX)
 PD8 USART3_TX USART3 NODMA
 PD9 USART3_RX USART3 NODMA
 
-# UART4 (GPS)
-PD1 UART4_TX UART4
-PD0 UART4_RX UART4
-
 # UART5 (SPORT)
 PC12 UART5_TX UART5 NODMA
 PD2  UART5_RX UART5 NODMA