An inflatable airbag assembly can include an airbag cushion and a vent tube having an aperture. Portions of one or more straps can be attached to opposite sides of the vent tube, and a release mechanism can selectively retain the one or more straps. Upon deployment of the airbag cushion while the release mechanism retains the one or more straps, the one or more straps can urge the opposite sides of the vent tube toward each other to assist in closing the aperture of the vent tube.