diff --git a/GeoLib/PolylineWithSegmentMarker.h b/GeoLib/PolylineWithSegmentMarker.h
index ab4fe86ebb2b72d91a65748e90c5623d2730296f..ca1b58be8a68373b582d634ae8308fd915bfe8c4 100644
--- a/GeoLib/PolylineWithSegmentMarker.h
+++ b/GeoLib/PolylineWithSegmentMarker.h
@@ -23,9 +23,9 @@ namespace GeoLib {
  * This is a polyline with the possibility to mark some segments. Thus class
  * PolylineWithSegmentMarker is derived from class Polyline.
  */
-class PolylineWithSegmentMarker: public GeoLib::Polyline {
+class PolylineWithSegmentMarker final : public GeoLib::Polyline {
 public:
-    PolylineWithSegmentMarker(GeoLib::Polyline const& polyline);
+    explicit PolylineWithSegmentMarker(GeoLib::Polyline const& polyline);
 
     /**
      * Method marks the segment (default mark is true).