diff --git a/libsrc/csg/extrusion.hpp b/libsrc/csg/extrusion.hpp
index af951c51..e29d5660 100644
--- a/libsrc/csg/extrusion.hpp
+++ b/libsrc/csg/extrusion.hpp
@@ -56,7 +56,7 @@ namespace netgen
 
     ~ExtrusionFace();
 
-    virtual void DoArchive(Archive& ar)
+    void DoArchive(Archive& ar) override
     {
       Surface::DoArchive(ar);
       ar & profile & path & glob_z_direction & deletable & spline3_path & line_path &
@@ -64,25 +64,25 @@ namespace netgen
         profile_spline_coeff & latest_seg & latest_t & latest_point2d & latest_point3d;
     }
   
-    virtual int IsIdentic (const Surface & s2, int & inv, double eps) const; 
+    int IsIdentic (const Surface & s2, int & inv, double eps) const override;
   
-    virtual double CalcFunctionValue (const Point<3> & point) const;
-    virtual void CalcGradient (const Point<3> & point, Vec<3> & grad) const;
-    virtual void CalcHesse (const Point<3> & point, Mat<3> & hesse) const;
-    virtual double HesseNorm () const;
+    double CalcFunctionValue (const Point<3> & point) const override;
+    void CalcGradient (const Point<3> & point, Vec<3> & grad) const override;
+    void CalcHesse (const Point<3> & point, Mat<3> & hesse) const override;
+    double HesseNorm () const override;
 
-    virtual double MaxCurvature () const;
+    double MaxCurvature () const override;
     //virtual double MaxCurvatureLoc (const Point<3> & /* c */ , 
     //				  double /* rad */) const;
 
-    virtual void Project (Point<3> & p) const;
+    void Project (Point<3> & p) const override;
 
-    virtual Point<3> GetSurfacePoint () const;
-    virtual void Print (ostream & str) const;
+    Point<3> GetSurfacePoint () const override;
+    void Print (ostream & str) const override;
   
-    virtual void GetTriangleApproximation (TriangleApproximation & tas, 
+    void GetTriangleApproximation (TriangleApproximation & tas, 
 					   const Box<3> & boundingbox, 
-					   double facets) const;
+					   double facets) const override;
 
     const SplineGeometry<3> & GetPath(void) const {return *path;}
     const SplineSeg<2> & GetProfile(void) const {return *profile;}
@@ -145,40 +145,39 @@ namespace netgen
     Extrusion() {}
     ~Extrusion();
 
-    virtual void DoArchive(Archive& ar)
+    void DoArchive(Archive& ar) override
     {
       Primitive::DoArchive(ar);
       ar & path & profile & z_direction & faces & latestfacenum;
     }
-    virtual INSOLID_TYPE BoxInSolid (const BoxSphere<3> & box) const;
-    virtual INSOLID_TYPE PointInSolid (const Point<3> & p,
-				       double eps) const;
+    INSOLID_TYPE BoxInSolid (const BoxSphere<3> & box) const override;
+    INSOLID_TYPE PointInSolid (const Point<3> & p,
+                               double eps) const override;
     INSOLID_TYPE PointInSolid (const Point<3> & p,
 			       double eps,
 			       NgArray<int> * const facenums) const;
 
-    virtual void GetTangentialSurfaceIndices (const Point<3> & p, 
-					      NgArray<int> & surfind, double eps) const;
+    void GetTangentialSurfaceIndices (const Point<3> & p, 
+                                      NgArray<int> & surfind, double eps) const override;
 
-    virtual INSOLID_TYPE VecInSolid (const Point<3> & p,
-				     const Vec<3> & v,
-				     double eps) const;
+    INSOLID_TYPE VecInSolid (const Point<3> & p,
+                             const Vec<3> & v,
+                             double eps) const override;
 
     // checks if lim s->0 lim t->0  p + t(v1 + s v2) in solid
-    virtual INSOLID_TYPE VecInSolid2 (const Point<3> & p,
-				      const Vec<3> & v1,
-				      const Vec<3> & v2,
-				      double eps) const;
+    INSOLID_TYPE VecInSolid2 (const Point<3> & p,
+                              const Vec<3> & v1,
+                              const Vec<3> & v2,
+                              double eps) const override;
 
   
-    virtual int GetNSurfaces() const;
-    virtual Surface & GetSurface (int i = 0);
-    virtual const Surface & GetSurface (int i = 0) const;
+    int GetNSurfaces() const override;
+    Surface & GetSurface (int i = 0) override;
+    const Surface & GetSurface (int i = 0) const override;
 
 
-    virtual void Reduce (const BoxSphere<3> & box);
-    virtual void UnReduce ();
-
+    void Reduce (const BoxSphere<3> & box) override;
+    void UnReduce () override;
   };
 
 }