diff --git a/Mesh_3/include/CGAL/internal/Mesh_3/helpers.h b/Mesh_3/include/CGAL/internal/Mesh_3/helpers.h
index 4095bb37baf..f51af8cd0b3 100644
--- a/Mesh_3/include/CGAL/internal/Mesh_3/helpers.h
+++ b/Mesh_3/include/CGAL/internal/Mesh_3/helpers.h
@@ -45,7 +45,7 @@ void dump_graph_edges(std::ostream& out, const Graph& g)
   typedef typename boost::graph_traits<Graph>::edge_descriptor edge_descriptor;
 
   out.precision(17);
-  for(edge_descriptor e : edges(g))
+  for(edge_descriptor e : CGAL::make_range(edges(g)))
   {
     vertex_descriptor s = source(e, g);
     vertex_descriptor t = target(e, g);
@@ -82,7 +82,7 @@ struct Angle_tester
       const typename Kernel::Point_3& p1 = g[v1];
       const typename Kernel::Point_3& p2 = g[v2];
 
-      return (CGAL::angle(p1, p, p2) == CGAL::ACUTE);
+      return (CGAL::angle(p1, p, p2) != CGAL::OBTUSE);
     }
   }
 };
diff --git a/Property_map/include/CGAL/property_map.h b/Property_map/include/CGAL/property_map.h
index 988c7ab6583..d57c53310e8 100644
--- a/Property_map/include/CGAL/property_map.h
+++ b/Property_map/include/CGAL/property_map.h
@@ -473,7 +473,7 @@ struct Constant_property_map
 
   typedef KeyType                                       key_type;
   typedef ValueType                                     value_type;
-  typedef value_type&                                   reference;
+  typedef const value_type&                             reference;
   typedef boost::read_write_property_map_tag            category;
 
   Constant_property_map(const value_type& default_value = value_type()) : default_value (default_value) { }