How does a ranger’s companion’s AC work with barding and there proficiency bonus?

@Mazoshi1987How does a ranger’s companion’s AC work with barding and there proficiency bonus? Do they stack? I believe so

— Mike Mearls (@mikemearls) May 10, 2016

@Mazoshi1987yes – I wouldn’t get fussy over that yes – I wouldn't get fussy over that

— Mike Mearls (@mikemearls) May 10, 2016