diff --git a/include/boost/optional/detail/optional_reference_spec.hpp b/include/boost/optional/detail/optional_reference_spec.hpp
index 4d1552f..105f790 100644
--- a/include/boost/optional/detail/optional_reference_spec.hpp
+++ b/include/boost/optional/detail/optional_reference_spec.hpp
@@ -122,7 +122,7 @@ public:
     
 #ifndef BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES   
  
-    optional(T&& rhs) BOOST_NOEXCEPT { detail::prevent_binding_rvalue<T&&>(); }
+    optional(T&& /* rhs */) BOOST_NOEXCEPT { detail::prevent_binding_rvalue<T&&>(); }
     
     template <class R>
         optional(R&& r, BOOST_DEDUCED_TYPENAME boost::enable_if<detail::is_no_optional<R> >::type* = 0) BOOST_NOEXCEPT