diff --git a/include/boost/intrusive/detail/key_nodeptr_comp.hpp b/include/boost/intrusive/detail/key_nodeptr_comp.hpp
index df2b895..98660c7 100644
--- a/include/boost/intrusive/detail/key_nodeptr_comp.hpp
+++ b/include/boost/intrusive/detail/key_nodeptr_comp.hpp
@@ -60,13 +60,13 @@ struct key_nodeptr_comp
 
    //key_forward
    template<class T>
-   typename enable_if<is_node_ptr<T>, const key_type &>::type
-      key_forward(const T &node) const
+   const key_type &key_forward
+      (const T &node, typename enable_if<is_node_ptr<T> >::type* =0) const
    {  return key_of_value()(*traits_->to_value_ptr(node));  }
 
    template<class T>
-   typename disable_if<is_node_ptr<T>, const T &>::type
-   const  key_forward(const T &key) const
+   const T &key_forward
+      (const T &key, typename disable_if<is_node_ptr<T> >::type* =0) const
    {  return key;  }
 
    //operator() 1 arg
diff --git a/include/boost/intrusive/detail/tree_value_compare.hpp b/include/boost/intrusive/detail/tree_value_compare.hpp
index 62817ca..dc55444 100644
--- a/include/boost/intrusive/detail/tree_value_compare.hpp
+++ b/include/boost/intrusive/detail/tree_value_compare.hpp
@@ -65,13 +65,13 @@ struct tree_value_compare
    {};
 
    template<class U>
-   typename boost::intrusive::detail::enable_if<is_key<U>, const key_type &>::type
-      key_forward(const U &key) const
+   const key_type & key_forward
+      (const U &key, typename boost::intrusive::detail::enable_if<is_key<U> >::type* = 0) const
    {  return key; }
 
    template<class U>
-   typename boost::intrusive::detail::disable_if<is_key<U>, const key_type &>::type
-      key_forward(const U &key) const
+   const key_type & key_forward
+      (const U &key, typename boost::intrusive::detail::disable_if<is_key<U> >::type* = 0) const
    {  return KeyOfValue()(key);  }
 
    template<class KeyType, class KeyType2>