The file boost/test/detail/basic_cstring/io.hpp contains this workaround function for GCC 2.95.3: template<typename CharT> inline std::ostream& operator<<( std::ostream& os, basic_cstring<CharT> const& str ) { typedef typename basic_cstring<CharT>::mutable_char char_type; char_type const* const beg = reinterpret_cast<char_type const* const>( str.b egin() ); char_type const* const end = reinterpret_cast<char_type const* const>( str.e nd() ); os << std::basic_string<char_type>( beg, end - beg ); return os; } What is mutable_char? It doesn't show up anywhere else in Boost. Doug