I'm trying to increase the number of bounded types stored in a boost::variant. It seems like I should be able to #define BOOST_MPL_LIMIT_LIST_SIZE in multiples of ten prior to inclusion of any boost headers but this doesn't seem to work for me. I haven't upgraded to the latest 1_32_0 release yet and am working with out-of-the-box 1_31_0 on Windows using the MS 7.1 compiler (VS .NET 2003). If for example I define BOOST_MPL_LIMIT_LIST_SIZE as: #define BOOST_MPL_LIMIT_LIST_SIZE 20 #include "my_boost_headers.h" I get an error: d:\ENCAPSULE-EXTLIB\boost\boost_1_31_0\boost_1_31_0\boost\variant\detail\make_variant_list.hpp(54) : error C2977: 'boost::mpl::list' : too many template arguments d:\ENCAPSULE-EXTLIB\boost\boost_1_31_0\boost_1_31_0\boost\mpl\aux_\preprocessed\plain\list.hpp(124) : see declaration of 'boost::mpl::list' d:\ENCAPSULE-EXTLIB\boost\boost_1_31_0\boost_1_31_0\boost\variant\detail\make_variant_list.hpp(59) : see reference to class template instantiation 'boost::detail::variant::make_variant_list' being compiled Shouldn't this just work? What am I missing here. TIA - Chris