diff --git a/libsrc/geom2d/python_geom2d.cpp b/libsrc/geom2d/python_geom2d.cpp
index 5b71b980..5ca29046 100644
--- a/libsrc/geom2d/python_geom2d.cpp
+++ b/libsrc/geom2d/python_geom2d.cpp
@@ -250,7 +250,7 @@ DLL_HEADER void ExportGeom2d(py::module &m)
 			  //cout << i << " : " << self.splines[i]->GetPoint(0.1) << " , " << self.splines[i]->GetPoint(0.5) << endl;
 		  }
 	  }))
-	  .def("GenerateMesh", FunctionPointer([](shared_ptr<SplineGeometry2d> self, MeshingParameters & mparam)
+	  .def("GenerateMesh", [](shared_ptr<SplineGeometry2d> self, MeshingParameters & mparam)
 		{
 		  shared_ptr<Mesh> mesh = make_shared<Mesh> ();
                   mesh->SetGeometry(self);
@@ -258,7 +258,7 @@ DLL_HEADER void ExportGeom2d(py::module &m)
                   ng_geometry = self;
 		  self->GenerateMesh(mesh, mparam);
 		  return mesh;
-	  }))
+                },py::call_guard<py::gil_scoped_release>())
 	  
 	  ;
   
diff --git a/libsrc/meshing/python_mesh.cpp b/libsrc/meshing/python_mesh.cpp
index f549981c..15595887 100644
--- a/libsrc/meshing/python_mesh.cpp
+++ b/libsrc/meshing/python_mesh.cpp
@@ -449,7 +449,7 @@ DLL_HEADER void ExportNetgenMeshing(py::module &m)
 
   py::implicitly_convertible< int, PointIndex>();
 
-  py::class_<NetgenGeometry, shared_ptr<NetgenGeometry>> (m, "NetgenGeometry")
+  py::class_<NetgenGeometry, shared_ptr<NetgenGeometry>> (m, "NetgenGeometry", py::dynamic_attr())
              ;
   
   py::class_<Mesh,shared_ptr<Mesh>>(m, "Mesh")
diff --git a/libsrc/occ/python_occ.cpp b/libsrc/occ/python_occ.cpp
index 34df71c0..2968638b 100644
--- a/libsrc/occ/python_occ.cpp
+++ b/libsrc/occ/python_occ.cpp
@@ -16,7 +16,7 @@ namespace netgen
 
 DLL_HEADER void ExportNgOCC(py::module &m) 
 {
-  py::class_<OCCGeometry, shared_ptr<OCCGeometry>> (m, "OCCGeometry", R"raw_string(Use LoadOCCGeometry to load the geometry from a *.step file.)raw_string")
+  py::class_<OCCGeometry, shared_ptr<OCCGeometry>, NetgenGeometry> (m, "OCCGeometry", R"raw_string(Use LoadOCCGeometry to load the geometry from a *.step file.)raw_string")
     .def(py::init<>())
     .def("Heal",[](OCCGeometry & self, double tolerance, bool fixsmalledges, bool fixspotstripfaces, bool sewfaces, bool makesolids, bool splitpartitions)
          {
diff --git a/libsrc/stlgeom/python_stl.cpp b/libsrc/stlgeom/python_stl.cpp
index 37d3e1fc..f8f04caa 100644
--- a/libsrc/stlgeom/python_stl.cpp
+++ b/libsrc/stlgeom/python_stl.cpp
@@ -18,7 +18,7 @@ namespace netgen
 
 DLL_HEADER void ExportSTL(py::module & m)
 {
-  py::class_<STLGeometry,shared_ptr<STLGeometry>> (m,"STLGeometry")
+  py::class_<STLGeometry,shared_ptr<STLGeometry>, NetgenGeometry> (m,"STLGeometry")
     .def(py::init<>())
     ;
   m.def("LoadSTLGeometry", FunctionPointer([] (const string & filename)
diff --git a/libsrc/stlgeom/stlgeom.hpp b/libsrc/stlgeom/stlgeom.hpp
index cb51cfae..7b1d814d 100644
--- a/libsrc/stlgeom/stlgeom.hpp
+++ b/libsrc/stlgeom/stlgeom.hpp
@@ -98,7 +98,7 @@ namespace netgen
 
 
 
-  class STLGeometry : public STLTopology, public NetgenGeometry
+  class STLGeometry : public NetgenGeometry, public STLTopology
   {
     // edges to be meshed:
     Array<STLEdge> edges;