We present a sound method for clustering alarms from static analyzers. Our method clusters alarms by discovering sound dependencies between them such that if the dominant alarm of a cluster turns out to be false (respectively true) then it is assured that all others in the same cluster are also false (respectively true). We have implemented our clustering algorithm on top of a realistic buffer-overflow analyzer and proved that our method has the effect of reducing 54% of alarm reur framework is applicable to any abstract interpretation-based nalysis and orthogonal to abstraction refinements and statistical ranking schemes.