The invention relates to an electro-hydraulic leak compensating device for a mobile crane lowering brake system in an open hydraulic circuit with a hydraulic motor (5) coupled with a lifting unit (6,7), a lowering brake valve (4) and a mechanical brake (9), with a pressure sensor (13) which measures the hydraulic pressure prevailing on the load side of the hydraulic motor (5) in the hydraulic circuit and on the side of the lifting conduit (3) before the mechanical brake (9) is closed, in particular immediately before it is closed, as well as a method of electro-hydraulically compensating for leaks of a mobile crane lowering brake system in an open hydraulic circuit with a hydraulic motor (5) coupled with a lifting unit (6,7), a lowering brake valve (4) and a mechanical brake (9), comprising the following method steps: measuring the hydraulic actual pressure prevailing on the load side of the hydraulic motor (5) before the mechanical brake (9) is closed, in particular immediately before it is closed; determining a desired pressure by setting off the measured actual pressure against a previously determined value depending on the load state; generating the desired pressure in the volume (12) before the mechanical brake (9) is opened.