diff --git a/STL_Extension/include/CGAL/Skiplist.h b/STL_Extension/include/CGAL/Skiplist.h
index 3be7908c90c..e7d7b60b422 100644
--- a/STL_Extension/include/CGAL/Skiplist.h
+++ b/STL_Extension/include/CGAL/Skiplist.h
@@ -75,7 +75,7 @@ public:
       all_iterator
     , typename all_list::iterator
     , T
-    >
+    , std::bidirectional_iterator_tag>
   {
   public:
     all_iterator() {}
@@ -91,7 +91,7 @@ public:
       skip_iterator
     , typename skip_list::iterator
     , T
-    >
+    , std::bidirectional_iterator_tag>
   {
   public:
     skip_iterator() {}
diff --git a/Triangulation_2/include/CGAL/Triangulation_2/internal/Polyline_constraint_hierarchy_2.h b/Triangulation_2/include/CGAL/Triangulation_2/internal/Polyline_constraint_hierarchy_2.h
index 8154e26251c..0cba5ca0213 100644
--- a/Triangulation_2/include/CGAL/Triangulation_2/internal/Polyline_constraint_hierarchy_2.h
+++ b/Triangulation_2/include/CGAL/Triangulation_2/internal/Polyline_constraint_hierarchy_2.h
@@ -85,7 +85,7 @@ public:
     Vertex_it
     , typename Vertex_list::skip_iterator
     , Vertex_handle
-    , boost::use_default
+    , std::bidirectional_iterator_tag
     , Vertex_handle>
   {
   public: