A surgical stapler includes an anvil assembly and a cartridge assembly. The anvil assembly defines staple forming depressions. One or both of the anvil assembly and the cartridge assembly are pivotable relative to the other between an open position and a clamped position. The cartridge assembly includes a first plurality of staples and a second plurality of staples. The first plurality of staples is initially positioned in alignment with the staple forming depressions of the anvil assembly for ejection from the cartridge assembly. The second plurality of staples is movably supported in the cartridge assembly from a first position misaligned with the staple forming depressions of the anvil assembly to a second position aligned with the staple forming depressions for subsequent ejection from the cartridge assembly.