Passing function with defaults as argument ignoring them

I need to convert a string that represents a vector of Ts into the corresponding vector.

My problem is that I'd like to pass a simple argument: the converter function. Here's the split:

template <class T>
auto split(const std::string &s, const std::function<T(const std::string&)> &convert, char sep = ',') -> std::vector<T>
{
    std::stringstream ss(s);
    std::vector<T> result;

    while (ss.good())
    {
        std::string substr;
        std::getline(ss, substr, sep);
        if (!substr.empty())
            result.push_back(convert(substr));
    }
    return result;
};

It fails to compile when passing standard functions such as std::stoi because of the default parameters of std::stoi:

auto q = split<int>(subs, std::stoi);

error: no matching function for call to 'split'
            auto q = split<int>(subs, std::stoi);
                     ^~~~~~~~~~

And obviously I can trick the compiler by using a lambda function:

auto q = split<std::size_t>(subs, [](const std::string &s){ return std::stoul(s); });

Is there a metaprogramming trick that allows me to somehow ignore the default parameters?