Assigning to a std::shared_ptr member variable

I have a class foo, with a member bar of type std::shared_ptr<int>:

class foo
{
    std::shared_ptr<int> bar;
    /*other stuff here*/
};

In that class I want to assign a new int to bar. But I can't write bar = new int(); as the pointer does not have a public assignment operator.

How should I do this? I could std::move or std::swap but neither of those seem right.