A closure for use with a beverage container, the closure having a plurality of compartments formed therein to store quantities of a flavoring agent separately from a mixing fluid (such as water) contained in the container. The compartments are operable by simple finger pressure to release their contents into the container one at a time for the purpose of making a flavored beverage. Support ribs are formed on the closure to allow the stacking of a number of closures or closure/container combinations without inadvertently releasing the flavoring agent from the compartments.