diff --git a/libsrc/meshing/improve3.cpp b/libsrc/meshing/improve3.cpp
index 071817e3..5ae6a103 100644
--- a/libsrc/meshing/improve3.cpp
+++ b/libsrc/meshing/improve3.cpp
@@ -521,7 +521,7 @@ void MeshOptimize3d :: CombineImprove (Mesh & mesh,
 
   // return CombineImproveSequential(mesh, goal);
 
-  mesh.BoundaryEdge (1,2); // ensure the boundary-elements table is built
+  mesh.BuildBoundaryEdges(false);
   
   int np = mesh.GetNP();
   int ne = mesh.GetNE();
@@ -817,7 +817,7 @@ void MeshOptimize3d :: SplitImprove (Mesh & mesh,
 
   PrintMessage (3, "SplitImprove");
   (*testout)  << "start SplitImprove" << "\n";
-  mesh.BoundaryEdge (1,2); // ensure the boundary-elements table is built
+  mesh.BuildBoundaryEdges(false);
 
   ParallelFor( mesh.VolumeElements().Range(), [&] (ElementIndex ei) NETGEN_LAMBDA_INLINE
     {
@@ -2713,7 +2713,7 @@ void MeshOptimize3d :: SwapImprove (Mesh & mesh, OPTIMIZEGOAL goal,
   int np = mesh.GetNP();
   int ne = mesh.GetNE();
 
-  mesh.BoundaryEdge (1,2); // ensure the boundary-elements table is built
+  mesh.BuildBoundaryEdges(false);
 
   auto elementsonnode = mesh.CreatePoint2ElementTable();
 
@@ -3932,7 +3932,7 @@ void MeshOptimize3d :: SwapImprove2 (Mesh & mesh, OPTIMIZEGOAL goal)
 
   // return SwapImprove2Sequential(mesh, goal);
 
-  mesh.BoundaryEdge (1,2); // ensure the boundary-elements table is built
+  mesh.BuildBoundaryEdges(false);
 
   int cnt = 0;
   double bad1, bad2;
@@ -4177,7 +4177,7 @@ void MeshOptimize3d :: SplitImprove2 (Mesh & mesh)
     }
   });
 
-  mesh.BoundaryEdge (1,2); // ensure the boundary-elements table is built
+  mesh.BuildBoundaryEdges(false);
 
   Array<std::tuple<double, ElementIndex>> split_candidates(ne);
   std::atomic<int> improvement_counter(0);
diff --git a/libsrc/meshing/meshclass.cpp b/libsrc/meshing/meshclass.cpp
index cac7dc97..3aff354b 100644
--- a/libsrc/meshing/meshclass.cpp
+++ b/libsrc/meshing/meshclass.cpp
@@ -1794,12 +1794,12 @@ namespace netgen
     volelements.SetAllocSize(nel);
   }
 
-
-  void Mesh :: BuildBoundaryEdges(void)
+  void Mesh :: BuildBoundaryEdges(bool rebuild)
   {
     static Timer t("Mesh::BuildBoundaryEdges"); RegionTimer reg(t);
     
-    // delete boundaryedges;
+    if(!rebuild && boundaryedges)
+      return;
 
     boundaryedges = make_unique<INDEX_2_CLOSED_HASHTABLE<int>>
       (3 * (GetNSE() + GetNOpenElements()) + GetNSeg() + 1);
diff --git a/libsrc/meshing/meshclass.hpp b/libsrc/meshing/meshclass.hpp
index 65ff082f..e3e61477 100644
--- a/libsrc/meshing/meshclass.hpp
+++ b/libsrc/meshing/meshclass.hpp
@@ -156,10 +156,10 @@ namespace netgen
     
     shared_ptr<NetgenGeometry> geometry;
 
-  private:
-    void BuildBoundaryEdges(void);
 
   public:
+    void BuildBoundaryEdges(bool rebuild=true);
+
     bool PointContainedIn2DElement(const Point3d & p,
 				   double lami[3],
 				   const int element,
diff --git a/libsrc/meshing/smoothing3.cpp b/libsrc/meshing/smoothing3.cpp
index e84a18ba..0f8652f6 100644
--- a/libsrc/meshing/smoothing3.cpp
+++ b/libsrc/meshing/smoothing3.cpp
@@ -1460,6 +1460,7 @@ void Mesh :: ImproveMesh (const MeshingParameters & mp, OPTIMIZEGOAL goal)
   static Timer trange("range");
 
   // return ImproveMeshSequential(mp, goal);
+  BuildBoundaryEdges(false);
 
   (*testout) << "Improve Mesh" << "\n";
   PrintMessage (3, "ImproveMesh");