The invention relates to a support for a system for fastening a rail on a substrate, having an angle bracket, which has a base section with a contact surface associated with the respective substrate, also having a supporting section, standing on the base section, which on its free front side associated with the rail to be fastened has a bearing surface, and also having a through hole formed in the base section for inserting a fastening element intended for fixing the angle bracket on the substrate. With such a support reliable support of the rail in service, also with greater tolerance for positioning the individual components, according to the invention is ensured by the fact that the through hole at least in a direction aligned parallel to the contact surface has an over-measure in relation to the circumference of the part, in the assembled condition sitting in the through hole, of the fastening element and by the fact that an additional locking piece, cooperating with the fastening element for fixing the angle bracket in a particular relative position obtained by a relative movement of fastening element and angle bracket, is also provided.