Hello, I have declared a GiNaC::parser l_parser; in a class method which is called in a multithread. If I show valgrind report I see: ==1084== Possible data race during write of size 1 at 0x1f06e4 by thread #3 ==1084== at 0x1B30F6: std::string::_Rep::_M_set_length_and_sharable(unsigned long) (in /usr/ lib/libstdc++.6.0.4.dylib) ==1084== by 0x1B39FB: std::string::_M_mutate(unsigned long, unsigned long, unsigned long) (in /usr/lib/libstdc++.6.0.4.dylib) ==1084== by 0x1B3A43: std::string::_M_replace_safe(unsigned long, unsigned long, char const*, unsigned long) (in /usr/lib/libstdc++. 6.0.4.dylib) ==1084== by 0x1B3AE7: std::string::assign(char const*, unsigned long) (in /usr/lib/libstdc++.6.0.4.dylib) ==1084== by 0x115D139: GiNaC::lexer::lexer(std::istream*, std::ostream*, std::ostream*) (in /Developer/opt/Ginac/1.5.8/lib/ libginac-1.5.0.dylib) ==1084== by 0x1157CC2: GiNaC::parser::parser(std::map<std::string, GiNaC::ex, std::less<std::string>, std::allocator<std::pair<std::string const, GiNaC::ex> > > const&, bool, std::map<std::pair<std::string, unsigned long>, GiNaC::ex (*) (std::vector<GiNaC::ex, std::allocator<GiNaC::ex> > const&), std::less<std::pair<std::string, unsigned long> >, std::allocator<std::pair<std::pair<std::string, unsigned long> const, GiNaC::ex (*)(std::vector<GiNaC::ex, std::allocator<GiNaC::ex> > const&)> > > const&) (in /Developer/opt/Ginac/1.5.8/lib/ libginac-1.5.0.dylib) When will be ginac thread safe and is there such a thing? Thx Phil