diff --git a/libraries/AP_GPS/AP_GPS_IMU.cpp b/libraries/AP_GPS/AP_GPS_IMU.cpp
index cc9d0667cf..9cfa79226a 100644
--- a/libraries/AP_GPS/AP_GPS_IMU.cpp
+++ b/libraries/AP_GPS/AP_GPS_IMU.cpp
@@ -223,4 +223,11 @@ void AP_GPS_IMU::checksum(byte data)
 {
         ck_a += data;
         ck_b += ck_a; 
-}
\ No newline at end of file
+}
+
+
+/****************************************************************
+ * Unused
+ ****************************************************************/
+void AP_GPS_IMU::setHIL(long time, float latitude, float longitude, float altitude,
+            float ground_speed, float ground_course, float speed_3d, uint8_t num_sats) {};
\ No newline at end of file
diff --git a/libraries/AP_GPS/AP_GPS_IMU.h b/libraries/AP_GPS/AP_GPS_IMU.h
index 5d4718da95..dd74463a19 100644
--- a/libraries/AP_GPS/AP_GPS_IMU.h
+++ b/libraries/AP_GPS/AP_GPS_IMU.h
@@ -20,6 +20,10 @@ class AP_GPS_IMU : public GPS {
         int     airspeed;
         float   imu_health;
         uint8_t imu_ok;
+		
+		// Unused
+		virtual void setHIL(long time, float latitude, float longitude, float altitude,
+            float ground_speed, float ground_course, float speed_3d, uint8_t num_sats);
 
   private:
         // Packet checksums