Hello, I want to create my own clock class, and in it among other things I would like to typedef a time_point<...>. struct MyClock { typedef int64_t rep; typedef boost::milli period; typedef boost::chrono::duration<rep,period> duration; typedef date_chrono::time_point<SystemClock,duration> time_point; static bool const is_monotonic = false; static time_point now(); }; Now, for this to work I obviously need to #include <boost/chrono/time_point.hpp>. Including it causes a dependency on Boost.System, making me have to link with it. But since I don't use any clocks provided by Boost.Chrono, I think the dependency on Boost.System is unnecessary. In fact, I was able to get rid of the dependency, and everything seems to work. I commented out 1 line from <boost/chrono/time_point.hpp>: //#include <boost/chrono/detail/system.hpp> Could this #include be removed from time_point.hpp, or is it needed for something I am not using ATM? Regards, Kris