Hello, I am using fusion v2 in my project and first would like to thank for the great lib. I installed this lib into the boost/fusion directory. Today I started using xpressive lib (which is also a great one!!!). Unfortunately xpressive broke my compilation, because it includes things from boost/spirit/fusion and my code includes headers from boost/fusion. Now my assumption: AFAIK spirit/fusion contains version 1. Since I would like to use version 2 I can not simply copy it into the spirit directory, since it can break other things like wave. Is it correct? If yes, does anyone have suggestions on how I should deal with this issues? Detailed compiler errors: E:\libraries\boost\include\boost/fusion/support/detail/access.hpp(24) : error C2953: 'boost::fusion::detail::ref_result' : class template has already been defined E:\libraries\boost\include\boost/spirit/fusion/detail/access.hpp(23) : see declaration of 'boost::fusion::detail::ref_result' E:\libraries\boost\include\boost/fusion/support/detail/access.hpp(34) : error C2953: 'boost::fusion::detail::cref_result' : class template has already been defined E:\libraries\boost\include\boost/spirit/fusion/detail/access.hpp(29) : see declaration of 'boost::fusion::detail::cref_result' E:\libraries\boost\include\boost/fusion/support/detail/access.hpp(40) : error C2953: 'boost::fusion::detail::non_ref_parameter' : class template has already been defined E:\libraries\boost\include\boost/spirit/fusion/detail/access.hpp(37) : see declaration of 'boost::fusion::detail::non_ref_parameter' E:\libraries\boost\include\boost/fusion/support/detail/access.hpp(52) : error C2953: 'boost::fusion::detail::call_param' : class template has already been defined E:\libraries\boost\include\boost/spirit/fusion/detail/access.hpp(43) : see declaration of 'boost::fusion::detail::call_param' With Kind Regards, Ovanes Markarian