A heat exchanger has a core comprising flat tubes with corrugated fins provided in spaces between tubes. An end mounting arrangement includes a mounting bracket for attachment to a housing. A fin support structure comprises a plurality of support walls and a plurality of axial walls, wherein each of the support walls is integrally joined to at least one of the axial walls, each of the support walls is in contact with the endmost corrugation of one of the fins, and each of the axial walls is in contact with one of the plate pairs. The fin support structure may have a corrugated structure, and is mounted at the end of the core at which the mounting bracket is provided, so as to support and minimize damage to the corrugated fins caused by bypass air flowing between the mounting bracket and the core.