A fluid cartridge, such as a cartridge for filling with ink for use in ink jet printhead includes a housing enclosing a wick chamber, the housing including a top wall. The housing also includes an ink chamber. A fluid conduit connects the ink chamber and the wick chamber. The outer surface of the top wall of the housing is formed with a recess. A vent opening through the top wall of the wick chamber, at the recess, provides communication between the wick chamber and the recess. A covering over the top surface of the housing encloses the recess. An outlet opening through an outer wall other than the top wall of the wick chamber provides fluid communication for the ink to flow from the wick chamber. One end of an overflow tube is in fluid communication with the recess in the top wall of the housing. The other end of the overflow tube opens to the ambient environment at another point on the exterior of the housing, such as near the outlet opening. A dam in the recess, between the vent opening and the one end of the overflow tube impedes, but does not completely obstruct the flow of spillover ink from the vent opening into the overflow tube.