Hi, I'm getting some test failures for inserting an initializer_list into the unordered containers: http://www.boost.org/development/tests/trunk/developer/output/teeks99-10-win... I don't have access to Visual C++ 12 to investigate this. This is just a guess, but I think the problem is converting an initializer_list of string literals to an initializer list of std::string. This works okay with clang and g++ so I assume it's allowed. A minimal test might be something like the following (although it might not). #include <initializer_list> #include <string> template <typename T> struct thing { void insert(T const&) {} void insert(T&&) {} void insert(std::initializer_list<T>) {} }; int main() { thing<std::string> x; x.insert("a"); x.insert({"a"}); x.insert({"a", "b"}); }