Hi, Under VC8 Express Edition: #include <functional> #include <boost/spirit/iterator/file_iterator.hpp> // greeting namespace your { struct plus { }; } namespace my { using namespace your; struct A : plus { }; // error C2872: 'plus' : ambiguous symbol } I don't know what happens, but 'using namespace std;' at <iterator/impl/file_iterator.ipp:line41> does something bad. Simplified Code: namespace standard { struct plus { }; } // almost like 'using namespace standard' under vc8? namespace fileiter_impl { // 'using-directive' here using namespace standard; // 'class template' here template< typename CharT > class std_file_iterator { }; } namespace your { struct plus { }; } namespace my { using namespace your; struct A : plus { }; // error C2872: 'plus' : ambiguous symbol } Regards, MB p-stade.sourceforge.net