diff --git a/libraries/AP_Common/Location.cpp b/libraries/AP_Common/Location.cpp
index 2d6688f488..55724896b3 100644
--- a/libraries/AP_Common/Location.cpp
+++ b/libraries/AP_Common/Location.cpp
@@ -339,3 +339,20 @@ bool Location::past_interval_finish_line(const Location &point1, const Location
     return this->line_path_proportion(point1, point2) >= 1.0f;
 }
 
+/*
+  return the proportion we are along the path from point1 to
+  point2, along a line parallel to point1<->point2.
+
+  This will be more than 1 if we have passed point2
+ */
+float Location::line_path_proportion(const Location &point1, const Location &point2) const
+{
+    const Vector2f vec1 = point1.get_distance_NE(point2);
+    const Vector2f vec2 = point1.get_distance_NE(*this);
+    const float dsquared = sq(vec1.x) + sq(vec1.y);
+    if (dsquared < 0.001f) {
+        // the two points are very close together
+        return 1.0f;
+    }
+    return (vec1 * vec2) / dsquared;
+}
diff --git a/libraries/AP_Common/Location.h b/libraries/AP_Common/Location.h
index 7b4c7890dd..cdfeb5341b 100644
--- a/libraries/AP_Common/Location.h
+++ b/libraries/AP_Common/Location.h
@@ -105,6 +105,13 @@ public:
     // the target waypoint
     bool past_interval_finish_line(const Location &point1, const Location &point2) const;
 
+    /*
+      return the proportion we are along the path from point1 to
+      point2, along a line parallel to point1<->point2.
+      This will be more than 1 if we have passed point2
+     */
+    float line_path_proportion(const Location &point1, const Location &point2) const;
+
 private:
     static AP_Terrain *_terrain;
 };
diff --git a/libraries/AP_Math/location.cpp b/libraries/AP_Math/location.cpp
index a289877bfb..cabcc811a1 100644
--- a/libraries/AP_Math/location.cpp
+++ b/libraries/AP_Math/location.cpp
@@ -39,27 +39,6 @@ float get_bearing_cd(const Vector3f &origin, const Vector3f &destination)
     return bearing;
 }
 
-/*
-  return the proportion we are along the path from point1 to
-  point2, along a line parallel to point1<->point2.
-
-  This will be less than >1 if we have passed point2
- */
-float location_path_proportion(const struct Location &location,
-                               const struct Location &point1,
-                               const struct Location &point2)
-{
-    const Vector2f vec1 = point1.get_distance_NE(point2);
-    const Vector2f vec2 = point1.get_distance_NE(location);
-    float dsquared = sq(vec1.x) + sq(vec1.y);
-    if (dsquared < 0.001f) {
-        // the two points are very close together
-        return 1.0f;
-    }
-    return (vec1 * vec2) / dsquared;
-}
-
-
 // return true when lat and lng are within range
 bool check_lat(float lat)
 {
diff --git a/libraries/AP_Math/location.h b/libraries/AP_Math/location.h
index 7c5afbf55a..b326c9d5a7 100644
--- a/libraries/AP_Math/location.h
+++ b/libraries/AP_Math/location.h
@@ -22,15 +22,6 @@ float        get_horizontal_distance_cm(const Vector3f &origin, const Vector3f &
 // return bearing in centi-degrees between two positions
 float        get_bearing_cd(const Vector3f &origin, const Vector3f &destination);
 
-/*
-  return the proportion we are along the path from point1 to
-  point2. This will be less than >1 if we have passed point2
- */
-float       location_path_proportion(const struct Location &location,
-                               const struct Location &point1,
-                               const struct Location &point2);
-
-
 // Converts from WGS84 geodetic coordinates (lat, lon, height)
 // into WGS84 Earth Centered, Earth Fixed (ECEF) coordinates
 // (X, Y, Z)