Using -std=c++11 on VS2015

I have created a shared object for Android in Visual Studio 2015.

It works fine so far, but pop_back() for a wstring does not work:

        wstring element = "JustATest!";
        if (element.back() == L'!')
        {
            element.pop_back();
        }

VS2015 tells me: "no member named 'pop_back' in 'std::basic_cstring<wchar_t>'".

Can anybody tell me how to get rid of this error? I have no idea why this should not work. Is that because for some reason VS2015 does not use C++11 here?

Thank you for the help!