Emplace to std::map of std::map

How can I emplace to std::map<std::string, std::map<std::string,std::string>>?

tried with myMap.emplace(std::make_pair("STRING", std::make_pair("STR","STR"))) but got error message cannot convert std::pair<_Ty1,_Ty2> to const std::pair<_Ty1,_Ty2>