An inkjet printhead includes: an elongate fluid manifold including a longitudinally extending channel having a pair of opposite longitudinal sidewalls and a base defining a floor of the channel; a plurality of printhead chips bonded to the base of the fluid manifold, each printhead chip receiving ink from fluid outlets defined in the floor of the channel; and a plurality of transverse ribs extending across the channel between the sidewalls, each transverse rib extending upwardly from the floor of the channel.