A reservoir including a housing having a chamber formed therein for the storage of hydraulic brake fluid. The chamber is in fluid communication with a master cylinder. The housing has an opening which is in communication with the atmosphere. The housing further including a passageway in communication with the cavity and the opening. A membrane is disposed in the passageway of the housing. The membrane has oleophobic properties such that the membrane permits the passage of air therethrough and substantially prevents the passage of brake fluid therethrough.