Hi, To take care of dependencies in my project using boost, I used to invoke gcc with the option -MM. However, since using boost 1.47, this does not work anymore. The precompiler aborts with the message: /usr/local/include/boost-1_47/boost/signals2/signal_type.hpp:29:2: error: #error This header requires BOOST_PARAMETER_MAX_ARITY to be defined as 7 or greater prior to including Boost.Parameter headers Because the macro BOOST_PARAMETER_MAX_ARITY plays no role whatsover in this invocation of gcc, I think that boost should solve their internal problem with the "arity" in some other way. In the mean time I define the macro in my make rules to generate the dependencies, but there it is obviously misplaced (any tips or tricks are welcome here). All the best, Ytsen.