I'm not certain if this is an asio issue or spirit2 issue (or user error). I checked Spirit out from the trunk and placed it into a 1.37 boost tree. I'm running gcc 4.3.2. Creating file foo.cpp with the following: --------------- #include <boost/asio.hpp> #include <boost/spirit/include/qi.hpp> --------------- Produces a string of errors including this snippet: from ../src/foo.cpp:3: ../../../library/vendor/boost/boost/proto/make_expr.hpp: At global scope: ../../../library/vendor/boost/boost/proto/make_expr.hpp:935: error: expected nested-name-specifier before numeric constant ../../../library/vendor/boost/boost/proto/make_expr.hpp:935: error: expected ‘>’ before numeric constant ../../../library/vendor/boost/boost/proto/make_expr.hpp:940: error: type/value mismatch at argument 3 in template parameter list for ‘template<class Tag, class DomainOrA0, class A0, class A1, class A2, class A3, class A4, class Void> struct boost::proto::result_of::make_expr’ ../../../library/vendor/boost/boost/proto/make_expr.hpp:940: error: expected a type, got ‘0’ ../../../library/vendor/boost/boost/proto/make_expr.hpp:940: error: expected initializer before ‘const’ Swapping the include order resolves the error. Should I enter a ticket? Michael -- ---------------------------------- Michael Caisse Object Modeling Designs www.objectmodelingdesigns.com