diff --git a/libraries/AP_Math/quaternion.h b/libraries/AP_Math/quaternion.h
index f6628c0d45485b..a5c44e2b49e05c 100644
--- a/libraries/AP_Math/quaternion.h
+++ b/libraries/AP_Math/quaternion.h
@@ -71,6 +71,10 @@ class QuaternionT {
 
     // convert a vector from body to earth frame
     void        body_to_earth(Vector3<T> &v) const;
+    // duplicate of body_to_earth for a compatibility lua binding alias for the old name for this function: earth_to_body. Remove this in 4.7
+    void        body_to_earth2(Vector3<T> &v) const {
+        body_to_earth(v);
+    }
 
     // create a quaternion from Euler angles using 321 euler ordering
     void        from_euler(T roll, T pitch, T yaw);