A printhead is provided having an elongate support having a plurality of internal webs protruding from a base section to define a plurality of parallel fluid supply channels, a shim supported by the support and defining a plurality of rows of openings through which fluid from respective supply channels is supplied, and a plurality of elongate printhead modules supported serially on the shim. Each module defines a plurality of fluid supply passages through which fluid passes to fluid ejection nozzles from respective rows of the openings. Either end of each module defines complementary formations such that adjacent modules nest together.