A surgical stapler, comprising: (a) an anvil half comprising: (i) an anvil channel member, (ii) an anvil surface having a plurality of staple forming pockets, and (iii) a projection coupled to a proximal portion of the anvil half; and (b) a cartridge half configured to releasably couple with the anvil half, wherein the cartridge half comprises: (i) a cartridge channel member having a distal portion configured to receive a staple cartridge, (ii) a latching lever pivotably coupled to the cartridge channel member, wherein the latching lever is pivotable between a closed position in which the latching lever engages and fixes the anvil channel member relative to the cartridge channel member, and an open position in which the latching lever disengages and permits movement of the anvil channel member relative to the cartridge channel member, and (iii) a locking member coupled to a proximal portion of the cartridge half, wherein the locking member is movable between a locked position in which the locking member captures the projection and thereby locks the proximal portion of the anvil half to the proximal portion of the cartridge half, and an unlocked position in which the locking member releases the projection and permits separation of the proximal portions, wherein the locking member is configured to assume the locked position when the latching lever is in the closed position, and the unlocked position when the latching lever is in the open position; and characterised in that the locking member is configured to translate along a longitudinal axis of the cartridge channel member between the unlocked position and the locked position. (a) an anvil half comprising: (i) an anvil channel member, (ii) an anvil surface having a plurality of staple forming pockets, and (iii) a projection coupled to a proximal portion of the anvil half; and (i) an anvil channel member, (ii) an anvil surface having a plurality of staple forming pockets, and (iii) a projection coupled to a proximal portion of the anvil half; and (b) a cartridge half configured to releasably couple with the anvil half, wherein the cartridge half comprises: (i) a cartridge channel member having a distal portion configured to receive a staple cartridge, (ii) a latching lever pivotably coupled to the cartridge channel member, wherein the latching lever is pivotable between a closed position in which the latching lever engages and fixes the anvil channel member relative to the cartridge channel member, and an open position in which the latching lever disengages and permits movement of the anvil channel member relative to the cartridge channel member, and (iii) a locking member coupled to a proximal portion of the cartridge half, (i) a cartridge channel member having a distal portion configured to receive a staple cartridge, (ii) a latching lever pivotably coupled to the cartridge channel member, wherein the latching lever is pivotable between a closed position in which the latching lever engages and fixes the anvil channel member relative to the cartridge channel member, and an open position in which the latching lever disengages and permits movement of the anvil channel member relative to the cartridge channel member, and (iii) a locking member coupled to a proximal portion of the cartridge half, wherein the locking member is movable between a locked position in which the locking member captures the projection and thereby locks the proximal portion of the anvil half to the proximal portion of the cartridge half, and an unlocked position in which the locking member releases the projection and permits separation of the proximal portions, wherein the locking member is configured to assume the locked position when the latching lever is in the closed position, and the unlocked position when the latching lever is in the open position; and characterised in that the locking member is configured to translate along a longitudinal axis of the cartridge channel member between the unlocked position and the locked position.