diff --git a/ROMFS/px4fmu_common/init.d/rc.sensors b/ROMFS/px4fmu_common/init.d/rc.sensors
index 0c75b8eb74..b6f9e4af4d 100644
--- a/ROMFS/px4fmu_common/init.d/rc.sensors
+++ b/ROMFS/px4fmu_common/init.d/rc.sensors
@@ -270,7 +270,11 @@ then
 	then
 	fi
 
-	if hmc5883 -R 4 start
+	if hmc5883 -I -R 4 start
+	then
+	fi
+
+	if hmc5883 -X start
 	then
 	fi
 fi
diff --git a/nuttx-configs/aerofc-v1/include/board.h b/nuttx-configs/aerofc-v1/include/board.h
index d4473e9555..bb5b77340e 100644
--- a/nuttx-configs/aerofc-v1/include/board.h
+++ b/nuttx-configs/aerofc-v1/include/board.h
@@ -255,6 +255,11 @@
  * reset the bus to clear stuck slaves.  They match the pin configuration,
  * but are normally-high GPIOs.
  */
+#define GPIO_I2C1_SDA GPIO_I2C1_SDA_2
+#define GPIO_I2C1_SCL GPIO_I2C1_SCL_2
+#define GPIO_I2C1_SDA_GPIO	(GPIO_OUTPUT|GPIO_OPENDRAIN|GPIO_SPEED_50MHz|GPIO_OUTPUT_SET|GPIO_PORTB|GPIO_PIN9)
+#define GPIO_I2C1_SCL_GPIO	(GPIO_OUTPUT|GPIO_OPENDRAIN|GPIO_SPEED_50MHz|GPIO_OUTPUT_SET|GPIO_PORTB|GPIO_PIN8)
+
 #define GPIO_I2C3_SDA		GPIO_I2C3_SDA_1
 #define GPIO_I2C3_SCL		GPIO_I2C3_SCL_1
 #define GPIO_I2C3_SDA_GPIO	(GPIO_OUTPUT|GPIO_OPENDRAIN|GPIO_SPEED_50MHz|GPIO_OUTPUT_SET|GPIO_PORTC|GPIO_PIN9)
diff --git a/src/drivers/boards/aerofc-v1/board_config.h b/src/drivers/boards/aerofc-v1/board_config.h
index f429b57fc6..3f47284cec 100644
--- a/src/drivers/boards/aerofc-v1/board_config.h
+++ b/src/drivers/boards/aerofc-v1/board_config.h
@@ -87,7 +87,8 @@
  * I2C3_SDL     PA8     COMPASS_I2C3_SCL          JP1-25,26
  *
  */
-#define PX4_I2C_BUS_ONBOARD    3
+#define PX4_I2C_BUS_EXPANSION	1
+#define PX4_I2C_BUS_ONBOARD		3
 
 #define PX4_I2C_OBDEV_HMC5883	0x1E