When use UTF8, non ASCII char is > 127, but char is signed, So get_index() return a big value. char c = -120; get_index(c) VC2010 say: boost::property_tree::detail::rapidxml::internal::get_index<char> returned 4294967168 unsigned int then internal::lookup_tables<0>::lookup_whitespace[internal::get_index(ch)] is error. My patch: inline size_t get_index(const Ch c) { // *** char c (ASCII / UTF8) and wchar_t c: 0 ~ 127 is ASCII char size_t r = c; //******** convert to unsigned // If not ASCII char, its sematic is same as plain 'z' // if (c > 255) //********* ASSCII is 0 to 127 if (r > 127) //******** check r, or check if(c < 0 || c > 127) { return 'z'; } return r; //******** return r } This is boost code: boost_1_46_0\boost\property_tree\detail\rapidxml.hpp template<class Ch> inline size_t get_index(const Ch c) { // If not ASCII char, its sematic is same as plain 'z' if (c > 255) { return 'z'; } return c; } // Detect whitespace character struct whitespace_pred { static unsigned char test(Ch ch) { return internal::lookup_tables<0>::lookup_whitespace[internal::get_index(ch)]; } }; // Detect node name character struct node_name_pred { static unsigned char test(Ch ch) { return internal::lookup_tables<0>::lookup_node_name[internal::get_index(ch)]; } };