How to create an std::function as method argument with std::stoi as default value?

I would like to use an std::function as an argument of a method and set its default value as std::stoi.

I tried the following code:

void test(std::function<int(const std::string& str, size_t *pos , int base)> inFunc=std::stoi)

Unfortunately I get the following error:

no viable conversion from '<overloaded function type>' to 'std::function<int (const std::string &, size_t *, int)>'

I managed to compile by adding creating a dedicated method.

#include <functional>
#include <string>


int my_stoi(const std::string& s)
{
    return std::stoi(s);
}

void test(std::function<int(const std::string&)> inFunc=my_stoi);

What's wrong in the first version? Isn't it possible to use std::stoi as default value?