diff --git a/Nef_3/include/CGAL/Nef_3/polygon_mesh_to_nef_3.h b/Nef_3/include/CGAL/Nef_3/polygon_mesh_to_nef_3.h
index c0076cfbca5..05af1c53542 100644
--- a/Nef_3/include/CGAL/Nef_3/polygon_mesh_to_nef_3.h
+++ b/Nef_3/include/CGAL/Nef_3/polygon_mesh_to_nef_3.h
@@ -205,6 +205,7 @@ void polygon_mesh_to_nef_3(const PolygonMesh& P, SNC_structure& S, FaceIndexMap
                  PolygonMesh, SNC_structure,HalfedgeIndexMap> index_adder(P,himap);
 
   for(vertex_descriptor pv : vertices(P) ) {
+    if (halfedge(pv, P) == boost::graph_traits<PolygonMesh>::null_halfedge()) continue; // skip isolated vertices
 
     typename boost::property_traits<PMap>::reference npv = get(pmap,pv);
     Vertex_handle nv = S.new_vertex();