A brake unit for a hydraulic brake system of a vehicle, having at least one fluid reservoir for the supply of a hydraulic pressure medium to the brake unit. The brake unit having a housing with at least one receiving seat for receiving a connector piece formed on the fluid reservoir, and at least one form-fitting fastening point provided for securing the fluid reservoir in position relative to the housing, the fastening point including at least one reservoir interface formed on the fluid reservoir, and at least one counterpart interface situated outside the fluid reservoir. In order to design an improved fastening interface which is positioned so as to be subjected to reduced load and which can be used with particularly compact and highly integrated hydraulic assemblies, it is proposed that the counterpart interface is arranged on a separate installation component connected to the housing.