A printhead assembly includes an elongate support structure; a series of wall sections extending a length of a first surface of the elongate support structure, the series of wall sections delineating ink supply channels therebetween; a plurality of carriers positioned end-to-end in the gap and supported by said edges of the walls, the carriers defining therethrough ink supply passages in fluid communication with the ink supply channels; a printhead integrated circuit mounted on each carrier to receive ink from respective ink supply channels; and a serrated channel extending a length of a second surface of the elongate support structure, the serrated channel for receiving fastening means therein.