diff --git a/libsrc/csg/python_csg.cpp b/libsrc/csg/python_csg.cpp
index 17458b90..11aae246 100644
--- a/libsrc/csg/python_csg.cpp
+++ b/libsrc/csg/python_csg.cpp
@@ -212,7 +212,7 @@ DLL_HEADER void ExportCSG(py::module &m)
 
   py::class_<SplineSurface, shared_ptr<SplineSurface>> (m, "SplineSurface",
                         "A surface for co dim 2 integrals on the splines")
-    .def("__init__", FunctionPointer  ([](SplineSurface* instance, shared_ptr<SPSolid> base, py::list cuts)
+    .def(py::init([](shared_ptr<SPSolid> base, py::list cuts)
 	     {
 	       auto primitive = dynamic_cast<OneSurfacePrimitive*> (base->GetSolid()->GetPrimitive());
 	       auto acuts = make_shared<NgArray<shared_ptr<OneSurfacePrimitive>>>();
@@ -225,12 +225,11 @@ DLL_HEADER void ExportCSG(py::module &m)
 		   if(sp)
 		     acuts->Append(shared_ptr<OneSurfacePrimitive>(sp));
 		   else
-		     throw NgException("Cut must be SurfacePrimitive in constructor of SplineSurface!");
+		     throw Exception("Cut must be SurfacePrimitive in constructor of SplineSurface!");
 		 }
 	       if(!primitive)
-		 throw NgException("Base is not a SurfacePrimitive in constructor of SplineSurface!");
-	       new (instance) SplineSurface(shared_ptr<OneSurfacePrimitive>(primitive),acuts);
-               py::object obj = py::cast(instance);
+		 throw Exception("Base is not a SurfacePrimitive in constructor of SplineSurface!");
+	       return make_shared<SplineSurface>(shared_ptr<OneSurfacePrimitive>(primitive),acuts);
 	     }),py::arg("base"), py::arg("cuts")=py::list())
     .def("AddPoint", FunctionPointer
 	 ([] (SplineSurface & self, double x, double y, double z, bool hpref)