A fastener driver includes a main housing, a drive blade movable from a retracted position to a driven position for driving a fastener into a workpiece, and a gas spring mechanism for driving the drive blade from the retracted position to the driven position. The gas spring mechanism includes a piston movable between a retracted position and a driven position. The fastener driver also includes an extensible cylinder for moving the drive blade from the driven position toward the retracted position. The extensible cylinder includes a cylinder housing coupled one of the main housing or the drive blade, and a rod coupled to the other of the main housing or the drive blade. A vacuum is created in the cylinder housing for biasing the drive blade toward the retracted position.