A liquid supply for an electronic smoking device has a liquid reservoir (110) within a housing (100) for holding a liquid. A buffering channel (120) within or on the housing (100) connects into the liquid reservoir (110) via a port (130). A sealing member (140) is fitted within the buffering channel (120) and provides a movable or slidable seal in the buffering channel (120). Upon expansion of a gas within the liquid reservoir (110) and/or a gaseous component within the liquid, the sealing member (140) moves within the buffering channel (120) to increase the effective volume of the liquid reservoir (110) and compensate for the change in pressure. Over-pressure and under-pressure conditions in the liquid reservoir are reduced or avoided.
