Overloading gives me error: no match for ‘operator<’

In code I have queue of Events sorted by waitTime. I want to find which Events should be executed for the current moment, so I do this:

std::vector<Event>::iterator up = std::upper_bound(queue.begin(), queue.end(), currentTime);

The std::upper_bound will work if I overload < operator:

bool Event::operator<(const double& currentTime) const
{
    return waitTime <= currentTime;
}

But I have an error:

   error: no match for ‘operator<’ (operand types are ‘const double’ and ‘Event’)

How should I correctly overload ‘operator<’ ?