An adapter for a quick-change system for changing attachments on a construction machine, which contains two parallel pin-like coupling elements arranged between parallel side parts at a stipulated spacing from each other for connection of the adapter to a quick coupler and a coupling member support releasably fastened to one of the coupling elements to secure the coupling elements. In order to permit simplified fastening, the coupling member support is connected directly to the pin-like coupling element secured against torsion via a releasable form-fit connection.