The purpose of this invention is a leak limiter (20) of an electrolytic cell (1) for the production of aluminum, fitted with confinement means comprising passage openings for the insertion of anode stems (3), characterized in that it comprises at least one support (21), capable of surrounding all or part of an anode stem, and at least one flexible sealing body (30, 30a, 30b, 30c) arranged around all or part of the periphery (23) of the support (21) and designed to close off all or some of the free space between the inside edge of an opening and an anode stem (3). This invention improves the leak tightness of covering means used in electrolytic cells.