diff --git a/include/boost/range/any_range.hpp b/include/boost/range/any_range.hpp
index ba4c224..9b7f87c 100644
--- a/include/boost/range/any_range.hpp
+++ b/include/boost/range/any_range.hpp
@@ -75,8 +75,8 @@ namespace boost
         template<
             class Value
           , class Traversal
-          , class Reference
-          , class Difference
+          , class Reference = Value&
+          , class Difference = std::ptrdiff_t
           , class Buffer = use_default
         >
         class any_range