Yeah, the unsafe version of things is only safe because HashMap has no interior mutability, and also relies on Player having no interior mutability. Also you still probably should not look at "yourself" through the map because writes to your &mut self ref are theoretically re-orderable to before or after the time when you're reading through the map. Other than that, if you start with the unique access to the hashmap, each pass of the loop will have unique assess to that particular player value for that iteration.