The present invention relates to a heat exchanger comprising a bundle for the exchange of heat between fluids, an endplate (10) of said bundle provided with orifices (11, 12) for the distribution of fluid through the bundle, and an adapter unit (20) with an external fluid circuit having one or more fluid-distribution ducts (21, 22) corresponding with one of said or with said distribution orifices of the endplate and being fixed by one face to the endplate, characterized in that the endplate (10) comprises at least one semi-cutout (110, 120) held by crimping in a housing (210, 220) formed in the face of the unit (20) in contact with the plate.