Abstract: An anti-closure device for use with a self-folding seat, including a seat portion and a tensioning system. The seat portion includes a first anchor that is adapted to be removably coupled to a seat of a self-folding seat, a second anchor that affixes to the seatback of the self folding seat or the seat portion of the adjacent seat, and the tensioning system is attached at a first end to the first anchor and at a second end to the second anchor. When installed on a self-folding seat, the tensioning system maintains force against a natural bias of the seat of the self-folding seat to fold closed, thereby holding the seat in an open state.