An end effector of a surgical stapling apparatus includes an anvil buttress and an anvil assembly. The anvil buttress has a proximal end portion including a strap. The anvil assembly includes an anvil body having a proximal end portion and a distal end portion. The proximal end portion has a tissue stop configured to prevent proximal tissue migration. The tissue stop includes a strap lock. The strap lock is configured to secure the strap of the anvil buttress to the anvil assembly to secure the anvil buttress to the anvil assembly.