A surgical stapling instrument comprising a replaceable staple cartridge is disclosed. The staple cartridge comprises a cartridge body comprising a proximal end, a distal end, and a longitudinal slot extending between the proximal end and the distal end. The staple cartridge further comprises a pan attachable to the cartridge body, wherein the pan is configured to prevent staples from falling out of a base of the cartridge body. The pan comprises a pan slot aligned with the longitudinal slot when the pan is attached to the cartridge body. The pan slot comprises a proximal portion comprising a first width and a distal portion comprising a second width. The first width is different than the second width.