A printhead assembly including a printhead module and a mounting structure is described. The printhead module is mounted on a receiving surface of the mounting structure and includes a first edge and a second edge opposite the first edge. The first and second edges extend beyond edges of the receiving surface by a first distance in a first direction and are positioned between featured edges of the mounting structure in a second direction that is substantially perpendicular to the first direction. Each featured edge includes a first feature protruding from the featured edge by a second distance in the first direction, where the second distance is greater than the first distance. The first features extend beyond the first and second edges of the printhead module. Each featured edge includes a recessed second feature configured to receive a first feature of a neighboring mounting structure.