An airbag has a skin enclosing a gas chamber and the skin has a vent which is closed in the resting state of the airbag and which opens when the pressure in the gas chamber exceeds a pre-determined value is described. The vent includes a vent hole in the skin and a tearable connection closing the vent hole in the resting state of the airbag. The airbag is folded to a package at least along a first direction and the tearable connection connects the skin around the vent hole directly to itself such that the tearable connection extends from a first point to a second point. In order to ensure that the vent remains closed during deployment and that the vent opens after the pressure inside the gas chamber exceeds a predetermined value within a rather small tolerance of the pressure, the line connecting the two points encloses an angle between 30° and 60° with the first direction.