A fastening assembly is provided for a roof add-on part of a motor vehicle, which has a roof skin element, an outer roof side frame, and a roof-add-on-part fastening element, which has a thread for detachably fastening the roof add-on part. The roof-add-on-part fastening element is fastened to a support plate. The support plate is arranged on a flange of the outer roof side frame and is fixed by a blind rivet only to the flange of the outer roof side frame, in such a way that the support plate and the flange of the outer roof side frame are jammed, in particular against each other.