Abstract: A liquid filled cover for a mattress having horizontally disposed upper and lower sheets of a material having a low resistance to penetration by fire and hot objects capable of initiating fire joined at their outermost edges to form a leakproof enclosure. After filling the enclosure with a fire extinguishing liquid, the filled height of the cover is relatively small as compared to its length and breadth. The upper sheet contains a closure for adding or removing liquid and a plurality of symmetrically opposed depressions within the upper and lower sheets of the liquid filled cover provide desired shape and load supporting characteristics. A retaining means positions and retains the cover to the top surface of a mattress. The liquid filled cover when interposed between a mattress and a sleeping occupant provides protection and warning to the occupant when the cover is punctured by fire or hot objects, whereby the released liquid acts to suppress the fire and awake the occupant.