diff --git a/libraries/AP_InertialSensor/AP_InertialSensor.h b/libraries/AP_InertialSensor/AP_InertialSensor.h
index 5f8615a8a8..efb90f7967 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor.h
+++ b/libraries/AP_InertialSensor/AP_InertialSensor.h
@@ -562,11 +562,11 @@ private:
     AccelCalibrator *_accel_calibrator;
 
     //save accelerometer bias and scale factors
-    void _acal_save_calibrations();
-    void _acal_event_failure();
+    void _acal_save_calibrations() override;
+    void _acal_event_failure() override;
 
     // Returns AccelCalibrator objects pointer for specified acceleromter
-    AccelCalibrator* _acal_get_calibrator(uint8_t i) { return i<get_accel_count()?&(_accel_calibrator[i]):nullptr; }
+    AccelCalibrator* _acal_get_calibrator(uint8_t i) override { return i<get_accel_count()?&(_accel_calibrator[i]):nullptr; }
 
     float _trim_pitch;
     float _trim_roll;
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_HIL.h b/libraries/AP_InertialSensor/AP_InertialSensor_HIL.h
index aad861f6ac..db2627da35 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor_HIL.h
+++ b/libraries/AP_InertialSensor/AP_InertialSensor_HIL.h
@@ -9,7 +9,7 @@ public:
     AP_InertialSensor_HIL(AP_InertialSensor &imu);
 
     /* update accel and gyro state */
-    bool update();
+    bool update() override;
 
     // detect the sensor
     static AP_InertialSensor_Backend *detect(AP_InertialSensor &imu);
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_PX4.h b/libraries/AP_InertialSensor/AP_InertialSensor_PX4.h
index 1a9e0a7264..65a91778c4 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor_PX4.h
+++ b/libraries/AP_InertialSensor/AP_InertialSensor_PX4.h
@@ -20,7 +20,7 @@ public:
     AP_InertialSensor_PX4(AP_InertialSensor &imu);
 
     /* update accel and gyro state */
-    bool update();
+    bool update() override;
 
     // detect the sensor
     static AP_InertialSensor_Backend *detect(AP_InertialSensor &imu);
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_SITL.h b/libraries/AP_InertialSensor/AP_InertialSensor_SITL.h
index 5166385131..be6d2a38b6 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor_SITL.h
+++ b/libraries/AP_InertialSensor/AP_InertialSensor_SITL.h
@@ -13,7 +13,7 @@ public:
     AP_InertialSensor_SITL(AP_InertialSensor &imu);
 
     /* update accel and gyro state */
-    bool update();
+    bool update() override;
 
     // detect the sensor
     static AP_InertialSensor_Backend *detect(AP_InertialSensor &imu);