Hi there, I am using boost v1.59 and I am having trouble in compiling a MSM state machine with more than 20 transitions. I followed the Q&A and added the following lines BEFORE any boost include: #define BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS #define BOOST_MPL_LIMIT_VECTOR_SIZE 30 // or whatever you need #define BOOST_MPL_LIMIT_MAP_SIZE 30 // or whatever you need but now instead of getting the previous error: error: wrong number of template arguments (21, should be 20) I get this one: /usr/local/include/boost/multi_index/tag.hpp:75:67: error: wrong number of template arguments (30, should be 20) mpl::vector<BOOST_PP_ENUM_PARAMS(BOOST_MULTI_INDEX_TAG_SIZE,T)>, I was just finishing this email when I found a solution. Adding only the following header #include "boost/mpl/vector/vector30.hpp" and explicitly declaring the transition table as a numbered mpl::vector (yep you have to count the rows...) struct transition_table : mpl::vector21< ... > solves the problem. Can you suggest me a better solution for this? Thanks! *Carlos Santos *