diff --git a/libraries/AP_InertialSensor/AP_InertialSensor.cpp b/libraries/AP_InertialSensor/AP_InertialSensor.cpp
index 52bfe9fd3e..7eb3830ddd 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor.cpp
+++ b/libraries/AP_InertialSensor/AP_InertialSensor.cpp
@@ -286,8 +286,7 @@ AP_InertialSensor::_init_accel(void (*flash_leds_cb)(bool on))
         }
 
         // null gravity from the Z accel
-        // TO-DO: replace with gravity #define form location.cpp
-        accel_offset.z += GRAVITY;
+        accel_offset.z += GRAVITY_MSS;
 
         total_change = fabsf(prev.x - accel_offset.x) + fabsf(prev.y - accel_offset.y) + fabsf(prev.z - accel_offset.z);
         max_offset = (accel_offset.x > accel_offset.y) ? accel_offset.x : accel_offset.y;
@@ -422,7 +421,7 @@ bool AP_InertialSensor::_calibrate_accel( Vector3f accel_sample[6],
 
     // reset
     beta[0] = beta[1] = beta[2] = 0;
-    beta[3] = beta[4] = beta[5] = 1.0f/GRAVITY;
+    beta[3] = beta[4] = beta[5] = 1.0f/GRAVITY_MSS;
     
     while( num_iterations < 20 && change > eps ) {
         num_iterations++;
@@ -452,9 +451,9 @@ bool AP_InertialSensor::_calibrate_accel( Vector3f accel_sample[6],
     }
 
     // copy results out
-    accel_scale.x = beta[3] * GRAVITY;
-    accel_scale.y = beta[4] * GRAVITY;
-    accel_scale.z = beta[5] * GRAVITY;
+    accel_scale.x = beta[3] * GRAVITY_MSS;
+    accel_scale.y = beta[4] * GRAVITY_MSS;
+    accel_scale.z = beta[5] * GRAVITY_MSS;
     accel_offsets.x = beta[0] * accel_scale.x;
     accel_offsets.y = beta[1] * accel_scale.y;
     accel_offsets.z = beta[2] * accel_scale.z;
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor.h b/libraries/AP_InertialSensor/AP_InertialSensor.h
index 96caf92daa..b6d6caaf1d 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor.h
+++ b/libraries/AP_InertialSensor/AP_InertialSensor.h
@@ -3,7 +3,6 @@
 #ifndef __AP_INERTIAL_SENSOR_H__
 #define __AP_INERTIAL_SENSOR_H__
 
-#define GRAVITY 9.80665f
 // Gyro and Accelerometer calibration criteria
 #define AP_INERTIAL_SENSOR_ACCEL_TOT_MAX_OFFSET_CHANGE  4.0f
 #define AP_INERTIAL_SENSOR_ACCEL_MAX_OFFSET             250.0f
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_MPU6000.cpp b/libraries/AP_InertialSensor/AP_InertialSensor_MPU6000.cpp
index 15e820a20a..09669b830c 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor_MPU6000.cpp
+++ b/libraries/AP_InertialSensor/AP_InertialSensor_MPU6000.cpp
@@ -6,7 +6,7 @@
 extern const AP_HAL::HAL& hal;
 
 // MPU6000 accelerometer scaling
-#define MPU6000_ACCEL_SCALE_1G    (GRAVITY / 4096.0f)
+#define MPU6000_ACCEL_SCALE_1G    (GRAVITY_MSS / 4096.0f)
 
 // MPU 6000 registers
 #define MPUREG_XG_OFFS_TC                               0x00
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_Oilpan.cpp b/libraries/AP_InertialSensor/AP_InertialSensor_Oilpan.cpp
index 26adf2b945..1749ec1257 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor_Oilpan.cpp
+++ b/libraries/AP_InertialSensor/AP_InertialSensor_Oilpan.cpp
@@ -24,7 +24,7 @@ const float AP_InertialSensor_Oilpan::_adc_constraint = 900;
 // Tested value : 418
 
 // Oilpan accelerometer scaling & offsets
-#define OILPAN_ACCEL_SCALE_1G   (GRAVITY * 2.0f / (2465.0f - 1617.0f))
+#define OILPAN_ACCEL_SCALE_1G   (GRAVITY_MSS * 2.0f / (2465.0f - 1617.0f))
 #define OILPAN_RAW_ACCEL_OFFSET ((2465.0f + 1617.0f) * 0.5f)
 #define OILPAN_RAW_GYRO_OFFSET  1658.0f
 
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_Oilpan.h b/libraries/AP_InertialSensor/AP_InertialSensor_Oilpan.h
index 98937819e0..f6678c94b4 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor_Oilpan.h
+++ b/libraries/AP_InertialSensor/AP_InertialSensor_Oilpan.h
@@ -39,8 +39,6 @@ private:
     static const int8_t         _sensor_signs[6];
     static const uint8_t        _gyro_temp_ch;
 
-    static const float          _gravity;
-
     static const float          _gyro_gain_x;
     static const float          _gyro_gain_y;
     static const float          _gyro_gain_z;