diff --git a/Polyhedron/demo/Polyhedron/Plugins/Mesh_3_plugin/Mesh_3_plugin_cgal_code.cpp b/Polyhedron/demo/Polyhedron/Plugins/Mesh_3_plugin/Mesh_3_plugin_cgal_code.cpp
index 49d9d257b1d..21af8a2a78f 100644
--- a/Polyhedron/demo/Polyhedron/Plugins/Mesh_3_plugin/Mesh_3_plugin_cgal_code.cpp
+++ b/Polyhedron/demo/Polyhedron/Plugins/Mesh_3_plugin/Mesh_3_plugin_cgal_code.cpp
@@ -23,7 +23,7 @@ typedef Mesh_criteria::Cell_criteria Cell_criteria;
 typedef Tr::Point Point_3;
 
 CGAL::Mesh_facet_topology topology(int manifold) {
-  return manifold == 1 ? CGAL::FACET_VERTICES_ON_SAME_SURFACE_PATCH :
+  return manifold == 0 ? CGAL::FACET_VERTICES_ON_SAME_SURFACE_PATCH :
     static_cast<CGAL::Mesh_facet_topology>
     (CGAL::MANIFOLD |
      CGAL::FACET_VERTICES_ON_SAME_SURFACE_PATCH);