diff --git a/GeoLib/Polyline.h b/GeoLib/Polyline.h
index 3de05b06663b3d5d632f13f9961c97bb676aa74e..83cbf53ea5e8d8d8644421eba13851adcc8e2564 100644
--- a/GeoLib/Polyline.h
+++ b/GeoLib/Polyline.h
@@ -118,7 +118,7 @@ public:
      * addition of the point would result in empty line segment \c false is
      * returned.
      */
-    bool addPoint(std::size_t pnt_id);
+    virtual bool addPoint(std::size_t pnt_id);
 
     /**
      * Method inserts a new point (that have to be inside the _ply_pnts vector)
@@ -131,7 +131,7 @@ public:
      * @return true if the point could be inserted, else false (if empty line
      * segments would be created).
      */
-    bool insertPoint(std::size_t pos, std::size_t pnt_id);
+    virtual bool insertPoint(std::size_t pos, std::size_t pnt_id);
 
     /**
      * Method removes a point from the polyline. The connecting line segments will