A linear cutter stapler includes an anvil jaw and a staple cartridge jaw. A post which projects from the anvil toward the staple cartridge includes a rounded crown dimensioned to self-seat in the cartridge. An abutment stop of the post abuts the cartridge to fix the spacing between the anvil and the cartridge when the jaws are closed. Alignment flanges, which project from the sides of the anvil, are received in notches formed in the sides of the cartridge jaw to stabilize the closed jaws. Both the post and the alignment flanges assure registration of staple shaping depressions formed in the anvil with the staples carried in the cartridge.