diff --git a/src/drivers/device/device.h b/src/drivers/device/device.h
index b65649d9da..813e1542bb 100644
--- a/src/drivers/device/device.h
+++ b/src/drivers/device/device.h
@@ -540,7 +540,8 @@ private:
 // class instance for primary driver of each class
 enum CLASS_DEVICE {
 	CLASS_DEVICE_PRIMARY=0,
-	CLASS_DEVICE_SECONDARY=1
+	CLASS_DEVICE_SECONDARY=1,
+	CLASS_DEVICE_TERTIARY=2
 };
 
 #endif /* _DEVICE_DEVICE_H */
diff --git a/src/drivers/drv_accel.h b/src/drivers/drv_accel.h
index a6abaec70f..1f98d966bd 100644
--- a/src/drivers/drv_accel.h
+++ b/src/drivers/drv_accel.h
@@ -83,6 +83,7 @@ struct accel_scale {
  */
 ORB_DECLARE(sensor_accel0);
 ORB_DECLARE(sensor_accel1);
+ORB_DECLARE(sensor_accel2);
 
 /*
  * ioctl() definitions
diff --git a/src/drivers/drv_gyro.h b/src/drivers/drv_gyro.h
index 3635cbce14..41b013a443 100644
--- a/src/drivers/drv_gyro.h
+++ b/src/drivers/drv_gyro.h
@@ -83,6 +83,7 @@ struct gyro_scale {
  */
 ORB_DECLARE(sensor_gyro0);
 ORB_DECLARE(sensor_gyro1);
+ORB_DECLARE(sensor_gyro2);
 
 /*
  * ioctl() definitions
diff --git a/src/drivers/drv_mag.h b/src/drivers/drv_mag.h
index a6c509d319..5ddf5d08e8 100644
--- a/src/drivers/drv_mag.h
+++ b/src/drivers/drv_mag.h
@@ -81,7 +81,7 @@ struct mag_scale {
  */
 ORB_DECLARE(sensor_mag0);
 ORB_DECLARE(sensor_mag1);
-
+ORB_DECLARE(sensor_mag2);
 
 /*
  * mag device types, for _device_id