diff --git a/Mesh_3/include/CGAL/Sizing_field_with_aabb_tree.h b/Mesh_3/include/CGAL/Sizing_field_with_aabb_tree.h
index 4957cbd98c3..cbfb48781b1 100644
--- a/Mesh_3/include/CGAL/Sizing_field_with_aabb_tree.h
+++ b/Mesh_3/include/CGAL/Sizing_field_with_aabb_tree.h
@@ -29,6 +29,7 @@
 #  include <boost/format.hpp>
 #endif  // CGAL_MESH_3_PROTECTION_HIGH_VERBOSITY || (! CGAL_NO_ASSERTIONS)
 
+namespace CGAL {
 /*!
 * @ingroup PkgMesh3DomainFields
 *
@@ -595,4 +596,6 @@ private:
   Facet_patch_id_map  facet_patch_id_map;
 };
 
+}//end namespace CGAL
+
 #endif // CGAL_MESH_3_SIZING_FIELD_WITH_AABB_TREE_H
diff --git a/Polyhedron/demo/Polyhedron/Plugins/Mesh_3/Mesh_function.h b/Polyhedron/demo/Polyhedron/Plugins/Mesh_3/Mesh_function.h
index 47987099312..ee687e78b68 100644
--- a/Polyhedron/demo/Polyhedron/Plugins/Mesh_3/Mesh_function.h
+++ b/Polyhedron/demo/Polyhedron/Plugins/Mesh_3/Mesh_function.h
@@ -253,7 +253,7 @@ edge_criteria(double edge_size, Mesh_fnt::Polyhedral_domain_tag)
 {
   if(p_.use_sizing_field_with_aabb_tree) {
     typedef typename Domain::Surface_patch_index_set Set_of_patch_ids;
-    typedef Sizing_field_with_aabb_tree<Kernel, Domain> Mesh_sizing_field; // type of sizing field for 0D and 1D features
+    typedef CGAL::Sizing_field_with_aabb_tree<Kernel, Domain> Mesh_sizing_field; // type of sizing field for 0D and 1D features
     typedef std::vector<Set_of_patch_ids> Patches_ids_vector;
     typedef typename Domain::Curve_index Curve_index;
     const Curve_index max_index = domain_->maximal_curve_index();