diff --git a/src/drivers/boards/px4fmu-v5/board_config.h b/src/drivers/boards/px4fmu-v5/board_config.h
index 730a0ed381..e6f83490c5 100644
--- a/src/drivers/boards/px4fmu-v5/board_config.h
+++ b/src/drivers/boards/px4fmu-v5/board_config.h
@@ -198,8 +198,12 @@
 #define PX4_I2C_BUS_EXPANSION	1
 #define PX4_I2C_BUS_EXPANSION1	2
 #define PX4_I2C_BUS_EXPANSION2	4
+#define PX4_I2C_BUS_EXPANSION3	3
 #define PX4_I2C_BUS_LED			PX4_I2C_BUS_EXPANSION
 
+#define BOARD_NUMBER_I2C_BUSES  4
+#define BOARD_I2C_BUS_CLOCK_INIT {100000, 100000, 100000, 100000}
+
 /* Devices on the external bus.
  *
  * Note that these are unshifted addresses.