An airbag comprises an airbag panel defining an inflatable volume. A discharge port having a closure is formed in the airbag panel. A tether extends through the inflatable volume from a first end tightly connected to the airbag panel in the direction of the discharge port to an opposite second end. The discharge port closure is connected to the second tether end and the airbag panel. The tether at least in portions has a two-ply design and includes two strap layers. A control strap extends transversely to the tether through the inflatable airbag volume. A first control strap portion is fastened to the airbag panel and to the first strap layer. A second control strap portion is fastened to the airbag panel and to the second strap layer.