Nullable types : by ref

I was trying to do something weird: I have a nullable type which encapsulate a struct (MouseState), and a function that takes a MouseState by ref:

  class Stuff
  {
    Nullable<MouseState> state = null;
    private void DoSomething(ref MouseState theState)
    { ... }
    public void Update()
    {
      if (state.HasValue)
      {
        DoSomething(ref state.Value);
      }
    }
  }

Of course, this code doesn't compile (you can't pass a value type which is the return value of a property as a ref to a function). The goal is obviously to avoid yet another a copy of the struct whne it's not null. Do I have any other way to do the same thing? Thanks for your help :)