Index: functional.hpp
===================================================================
--- functional.hpp	(revision 83352)
+++ functional.hpp	(working copy)
@@ -246,14 +246,21 @@
 
         template<typename Left, typename Right, typename EnableIf>
         struct average_base
-          : functional::divides<Left, Right>
-        {};
+        {
+            // Define the type of the result
+            typedef typename functional::divides<Left, Right>::result_type result_type;
 
+            result_type operator()(Left & left, Right & right) const
+            {
+                return numeric::divides(numeric::plus(left, right), 2);
+            }
+        };
+
         // partial specialization that promotes the arguments to double for
         // integral division.
         template<typename Left, typename Right>
         struct average_base<Left, Right, typename enable_if<are_integral<Left, Right> >::type>
-          : functional::divides<double const, double const>
+          : average_base<double const, double const>
         {};
 
         template<typename To, typename From, typename EnableIf>