Why does std::future::wait_for not behave as expected?

#include <iostream>
#include <chrono>
#include <future>

using namespace std::literals;

int main()
{
    std::promise<void> prom;
    auto               fut = prom.get_future();

    std::cout << std::boolalpha << (
         std::future_status::timeout ==
         fut.wait_for(std::chrono::seconds::max())
    );
}

The code should output nothing, because fut.wait_for will wait for a very very long time. However, it outputs true in no time!

Why does std::future::wait_for not behave as expected?