Hi, The function get is defined in the documentation with following prototypes R&& unique_future::get(); R& unique_future<R&>::get(); void unique_future<void>::get(); But when the move semantic is emulated this is just translated as move_dest_type get() with move_dest_type defined depending on the future template parameter as follows typedef typename detail::future_traits<R>::move_dest_type move_dest_type; template<typename T> struct future_traits { #ifdef BOOST_HAS_RVALUE_REFS typedef T const& source_reference_type; struct dummy; typedef typename boost::mpl::if_<boost::is_fundamental<T>,dummy&,T&&>::type rvalue_source_type; typedef typename boost::mpl::if_<boost::is_fundamental<T>,T,T&&>::type move_dest_type; #else typedef T& source_reference_type; typedef typename boost::mpl::if_<boost::is_convertible<T&,boost::detail::thread_move_t<T> >,boost::detail::thread_move_t<T>,T const&>::type rvalue_source_type; typedef typename boost::mpl::if_<boost::is_convertible<T&,boost::detail::thread_move_t<T> >,boost::detail::thread_move_t<T>,T>::type move_dest_type; #endif }; Generic libraries using the futures needs to get the type returned by get. What do you think about making the move_dest_type public at least when BOOST_HAS_RVALUE_REFS is not defined? Another option would be to make public the future_traits class. Best, Vicente