diff --git a/Mesh_3/demo/Mesh_3/Polyhedron_type_fwd.h b/Mesh_3/demo/Mesh_3/Polyhedron_type_fwd.h
index 993ff0d1bfd..8caa451dd3a 100644
--- a/Mesh_3/demo/Mesh_3/Polyhedron_type_fwd.h
+++ b/Mesh_3/demo/Mesh_3/Polyhedron_type_fwd.h
@@ -17,8 +17,10 @@ namespace CGAL {
 
 #ifndef CGAL_CFG_NO_TMPL_IN_TMPL_PARAM
   template < class T, class I, class A>
-#endif
+  class HalfedgeDS_default;
+#else
   struct HalfedgeDS_default;
+#endif
 
   template < class PolyhedronTraits_3,
              class PolyhedronItems_3,