diff --git a/ArduCopter/APM_Config.h b/ArduCopter/APM_Config.h
index 865914316d..33accb17c1 100644
--- a/ArduCopter/APM_Config.h
+++ b/ArduCopter/APM_Config.h
@@ -24,7 +24,7 @@
 //#define AUTOTUNE_ENABLED      DISABLED            // disable the auto tune functionality to save 7k of flash
 //#define AC_FENCE              DISABLED            // disable fence to save 2k of flash
 //#define CAMERA                DISABLED            // disable camera trigger to save 1k of flash
-//#define CONFIG_SONAR          DISABLED            // disable sonar to save 1k of flash
+//#define RANGEFINDER_ENABLED   DISABLED            // disable rangefinder to save 1k of flash
 //#define POSHOLD_ENABLED       DISABLED            // disable PosHold flight mode to save 4.5k of flash
 //#define AC_RALLY              DISABLED            // disable rally points library (must also disable terrain which relies on rally)
 //#define AC_TERRAIN            DISABLED            // disable terrain library
diff --git a/ArduCopter/Copter.h b/ArduCopter/Copter.h
index b42c61632f..92b9e2623f 100644
--- a/ArduCopter/Copter.h
+++ b/ArduCopter/Copter.h
@@ -169,7 +169,7 @@ private:
     Compass compass;
     AP_InertialSensor ins;
 
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
     RangeFinder sonar {serial_manager};
     bool sonar_enabled; // enable user switch for sonar
 #endif
diff --git a/ArduCopter/GCS_Mavlink.cpp b/ArduCopter/GCS_Mavlink.cpp
index af764c63ae..d175af2cc5 100644
--- a/ArduCopter/GCS_Mavlink.cpp
+++ b/ArduCopter/GCS_Mavlink.cpp
@@ -249,7 +249,7 @@ NOINLINE void Copter::send_extended_status1(mavlink_channel_t chan)
     }
 #endif
 
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
     if (sonar.num_sensors() > 0) {
         control_sensors_present |= MAV_SYS_STATUS_SENSOR_LASER_POSITION;
         control_sensors_enabled |= MAV_SYS_STATUS_SENSOR_LASER_POSITION;
@@ -409,7 +409,7 @@ void NOINLINE Copter::send_current_waypoint(mavlink_channel_t chan)
     mavlink_msg_mission_current_send(chan, mission.get_current_nav_index());
 }
 
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
 void NOINLINE Copter::send_rangefinder(mavlink_channel_t chan)
 {
     // exit immediately if sonar is disabled
@@ -633,7 +633,7 @@ bool GCS_MAVLINK::try_send_message(enum ap_message id)
         break;
 
     case MSG_RANGEFINDER:
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
         CHECK_PAYLOAD_SIZE(RANGEFINDER);
         copter.send_rangefinder(chan);
 #endif
diff --git a/ArduCopter/Parameters.cpp b/ArduCopter/Parameters.cpp
index ccc972d68b..0785673f16 100644
--- a/ArduCopter/Parameters.cpp
+++ b/ArduCopter/Parameters.cpp
@@ -895,7 +895,7 @@ const AP_Param::Info Copter::var_info[] = {
     // @Path: ../libraries/AP_RSSI/AP_RSSI.cpp
     GOBJECT(rssi, "RSSI_",  AP_RSSI),      
     
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
     // @Group: RNGFND
     // @Path: ../libraries/AP_RangeFinder/RangeFinder.cpp
     GOBJECT(sonar,   "RNGFND", RangeFinder),
diff --git a/ArduCopter/arming_checks.cpp b/ArduCopter/arming_checks.cpp
index bb35cc8a8a..0a7775865d 100644
--- a/ArduCopter/arming_checks.cpp
+++ b/ArduCopter/arming_checks.cpp
@@ -317,7 +317,7 @@ bool Copter::pre_arm_checks(bool display_failure)
             return false;
         }
 
-        #if CONFIG_SONAR == ENABLED && OPTFLOW == ENABLED
+        #if RANGEFINDER_ENABLED == ENABLED && OPTFLOW == ENABLED
         // check range finder if optflow enabled
         if (optflow.enabled() && !sonar.pre_arm_check()) {
             if (display_failure) {
diff --git a/ArduCopter/config.h b/ArduCopter/config.h
index c2c356538b..94075e60cd 100644
--- a/ArduCopter/config.h
+++ b/ArduCopter/config.h
@@ -48,8 +48,8 @@
 #endif
 
 #if HIL_MODE != HIL_MODE_DISABLED       // we are in HIL mode
- #undef CONFIG_SONAR
- #define CONFIG_SONAR DISABLED
+ #undef RANGEFINDER_ENABLED
+ #define RANGEFINDER_ENABLED DISABLED
 #endif
 
 #define MAGNETOMETER ENABLED
@@ -125,8 +125,8 @@
 // Sonar
 //
 
-#ifndef CONFIG_SONAR
- # define CONFIG_SONAR ENABLED
+#ifndef RANGEFINDER_ENABLED
+ # define RANGEFINDER_ENABLED ENABLED
 #endif
 
 #ifndef SONAR_ALT_HEALTH_MAX
diff --git a/ArduCopter/control_land.cpp b/ArduCopter/control_land.cpp
index 5dd65833b8..e4bb636e1b 100644
--- a/ArduCopter/control_land.cpp
+++ b/ArduCopter/control_land.cpp
@@ -233,7 +233,7 @@ void Copter::land_nogps_run()
 //      should be called at 100hz or higher
 float Copter::get_land_descent_speed()
 {
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
     bool sonar_ok = sonar_enabled && (sonar.status() == RangeFinder::RangeFinder_Good);
 #else
     bool sonar_ok = false;
diff --git a/ArduCopter/sensors.cpp b/ArduCopter/sensors.cpp
index 232d9fda8a..49d5e8537d 100644
--- a/ArduCopter/sensors.cpp
+++ b/ArduCopter/sensors.cpp
@@ -26,7 +26,7 @@ void Copter::read_barometer(void)
     motors.set_air_density_ratio(barometer.get_air_density_ratio());
 }
 
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
 void Copter::init_sonar(void)
 {
    sonar.init();
@@ -36,7 +36,7 @@ void Copter::init_sonar(void)
 // return sonar altitude in centimeters
 int16_t Copter::read_sonar(void)
 {
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
     sonar.update();
 
     // exit immediately if sonar is disabled
diff --git a/ArduCopter/switches.cpp b/ArduCopter/switches.cpp
index 03d95ef899..de733d47ac 100644
--- a/ArduCopter/switches.cpp
+++ b/ArduCopter/switches.cpp
@@ -347,7 +347,7 @@ void Copter::do_aux_switch_function(int8_t ch_function, uint8_t ch_flag)
 
         case AUXSW_SONAR:
             // enable or disable the sonar
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
             if (ch_flag == AUX_SWITCH_HIGH) {
                 sonar_enabled = true;
             }else{
diff --git a/ArduCopter/system.cpp b/ArduCopter/system.cpp
index e035a0a089..97f8485698 100644
--- a/ArduCopter/system.cpp
+++ b/ArduCopter/system.cpp
@@ -257,7 +257,7 @@ void Copter::init_ardupilot()
     init_barometer(true);
 
     // initialise sonar
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
     init_sonar();
 #endif
 
diff --git a/ArduCopter/terrain.cpp b/ArduCopter/terrain.cpp
index 45d91ed90f..b9cf9243d2 100644
--- a/ArduCopter/terrain.cpp
+++ b/ArduCopter/terrain.cpp
@@ -10,7 +10,7 @@ void Copter::terrain_update()
 
     // tell the rangefinder our height, so it can go into power saving
     // mode if available
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
     float height;
     if (terrain.height_above_terrain(height, true)) {
         sonar.set_estimated_terrain_height(height);
diff --git a/ArduCopter/test.cpp b/ArduCopter/test.cpp
index 3bc6e499de..1f5dab70a3 100644
--- a/ArduCopter/test.cpp
+++ b/ArduCopter/test.cpp
@@ -245,7 +245,7 @@ int8_t Copter::test_shell(uint8_t argc, const Menu::arg *argv)
  */
 int8_t Copter::test_sonar(uint8_t argc, const Menu::arg *argv)
 {
-#if CONFIG_SONAR == ENABLED
+#if RANGEFINDER_ENABLED == ENABLED
 	sonar.init();
 
     cliSerial->printf("RangeFinder: %d devices detected\n", sonar.num_sensors());