diff --git boost/token_functions.hpp boost/token_functions.hpp
index 4d1a1df..1f24efa 100644
--- boost/token_functions.hpp
+++ boost/token_functions.hpp
@@ -309,7 +309,7 @@ namespace boost{
   template <>
   struct assign_or_plus_equal<std::input_iterator_tag> {
     template<class Iterator, class Token>
-    static void assign(Iterator b, Iterator e, Token &t) { }
+    static void assign(Iterator, Iterator, Token &) { }
     template<class Token, class Value> 
     static void plus_equal(Token &t, const Value &v) {
       t += v;