[boost] [date_time] missing includes?

I'm just trying date_time on OS X. I've included #include <boost/date_time/posix_time/ptime.hpp> #include <boost/date_time/posix_time/conversion.hpp> This fails to compile with the following error. Including posix_time.hpp rather than ptime.hpp or a gregorian header solves the problem. posix_time/conversion.hpp:33: error: 'to_tm' undeclared in namespace 'boost::gergorian' posix_time/conversion.hpp:45: error: 'date_from_tm' undeclared in namespace 'boost::gregorian' Should the appropriate header be included by posix_time/conversion.hpp? Cheers Russell