In one aspect, an apparatus for helping to protect an occupant of a vehicle includes a frontal curtain airbag. The airbag has overlying panels that are interconnected. The airbag is deployable a deployed condition in which the airbag spans across a width of a windshield opening of the vehicle. A restraining panel is separate from and extends widthwise over the panels of the airbag. The restraining panel is connected to the airbag and has a width configured to cause opposing end portions of the deployed airbag to be bent toward one another and into a curved configuration. Pressurization in the deploying airbag tensions the restraining panel widthwise. The tensioned restraining panel maintains the bend in the deploying airbag so that an effective airbag depth is measured between the restraining panel and the airbag.