An ink cartridge for an inkjet printer includes a bottom face and a front face; an ink interface on the front face of the ink cartridge for connection to a cartridge receiving structure; a guide interface in the bottom face for guiding the cartridge along a straight line during insertion into the cartridge receiving structure for connecting the ink interface; a latch track disposed in the bottom face of the ink cartridge to guide a latch of the cartridge receiving structure; a latch stop disposed in the latch track for engaging the latch, where the latch track comprises a locking track and an unlocking track to accommodate movement of the latch with respect to the latch stop, the locking track being at least partly separate from the unlocking track; and a latch guide for redirecting the latch towards the locking track, rather than the unlocking track.