diff --git a/libraries/AC_WPNav/AC_Circle.cpp b/libraries/AC_WPNav/AC_Circle.cpp
index 36900b12d5..6d48ed8ffe 100644
--- a/libraries/AC_WPNav/AC_Circle.cpp
+++ b/libraries/AC_WPNav/AC_Circle.cpp
@@ -358,7 +358,7 @@ bool AC_Circle::get_terrain_offset(float& offset_cm)
         return false;
     case AC_Circle::TerrainSource::TERRAIN_FROM_RANGEFINDER:
         if (_rangefinder_healthy) {
-            offset_cm = _inav.get_position_z_up_cm() - _rangefinder_alt_cm;
+            offset_cm = _rangefinder_terrain_offset_cm;
             return true;
         }
         return false;
diff --git a/libraries/AC_WPNav/AC_Circle.h b/libraries/AC_WPNav/AC_Circle.h
index 94f578042c..88dd03c02c 100644
--- a/libraries/AC_WPNav/AC_Circle.h
+++ b/libraries/AC_WPNav/AC_Circle.h
@@ -89,8 +89,9 @@ public:
     /// true if pilot control of radius and turn rate is enabled
     bool pilot_control_enabled() const { return (_options.get() & CircleOptions::MANUAL_CONTROL) != 0; }
 
-    /// provide rangefinder altitude
-    void set_rangefinder_alt(bool use, bool healthy, float alt_cm) { _rangefinder_available = use; _rangefinder_healthy = healthy; _rangefinder_alt_cm = alt_cm; }
+    /// provide rangefinder based terrain offset
+    /// terrain offset is the terrain's height above the EKF origin
+    void set_rangefinder_terrain_offset(bool use, bool healthy, float terrain_offset_cm) { _rangefinder_available = use; _rangefinder_healthy = healthy; _rangefinder_terrain_offset_cm = terrain_offset_cm;}
 
     /// check for a change in the radius params
     void check_param_change();
@@ -159,5 +160,5 @@ private:
     bool        _terrain_alt;           // true if _center.z is alt-above-terrain, false if alt-above-ekf-origin
     bool        _rangefinder_available; // true if range finder could be used
     bool        _rangefinder_healthy;   // true if range finder is healthy
-    float       _rangefinder_alt_cm;    // latest rangefinder altitude
+    float       _rangefinder_terrain_offset_cm; // latest rangefinder based terrain offset (e.g. terrain's height above EKF origin)
 };
diff --git a/libraries/AC_WPNav/AC_WPNav.cpp b/libraries/AC_WPNav/AC_WPNav.cpp
index e6153293f6..c18e9392c7 100644
--- a/libraries/AC_WPNav/AC_WPNav.cpp
+++ b/libraries/AC_WPNav/AC_WPNav.cpp
@@ -629,7 +629,7 @@ bool AC_WPNav::get_terrain_offset(float& offset_cm)
         return false;
     case AC_WPNav::TerrainSource::TERRAIN_FROM_RANGEFINDER:
         if (_rangefinder_healthy) {
-            offset_cm = _inav.get_position_z_up_cm() - _rangefinder_alt_cm;
+            offset_cm = _rangefinder_terrain_offset_cm;
             return true;
         }
         return false;
diff --git a/libraries/AC_WPNav/AC_WPNav.h b/libraries/AC_WPNav/AC_WPNav.h
index fa1ff69ee9..8b0a02107e 100644
--- a/libraries/AC_WPNav/AC_WPNav.h
+++ b/libraries/AC_WPNav/AC_WPNav.h
@@ -22,8 +22,9 @@ public:
     /// Constructor
     AC_WPNav(const AP_InertialNav& inav, const AP_AHRS_View& ahrs, AC_PosControl& pos_control, const AC_AttitudeControl& attitude_control);
 
-    /// provide rangefinder altitude
-    void set_rangefinder_alt(bool use, bool healthy, float alt_cm) { _rangefinder_available = use; _rangefinder_healthy = healthy; _rangefinder_alt_cm = alt_cm; }
+    /// provide rangefinder based terrain offset
+    /// terrain offset is the terrain's height above the EKF origin
+    void set_rangefinder_terrain_offset(bool use, bool healthy, float terrain_offset_cm) { _rangefinder_available = use; _rangefinder_healthy = healthy; _rangefinder_terrain_offset_cm = terrain_offset_cm;}
 
     // return true if range finder may be used for terrain following
     bool rangefinder_used() const { return _rangefinder_use; }
@@ -280,5 +281,5 @@ protected:
     bool        _rangefinder_available; // true if rangefinder is enabled (user switch can turn this true/false)
     AP_Int8     _rangefinder_use;       // parameter that specifies if the range finder should be used for terrain following commands
     bool        _rangefinder_healthy;   // true if rangefinder distance is healthy (i.e. between min and maximum)
-    float       _rangefinder_alt_cm;    // latest distance from the rangefinder
+    float       _rangefinder_terrain_offset_cm; // latest rangefinder based terrain offset (e.g. terrain's height above EKF origin)
 };