Abstract: Coverage-based fault localization is a statistical technique that assists developers in finding faulty entities efficiently by contrasting program traces. Although coverage-based fault localization has been shown to be promising, its effectiveness still suffers from occurrences of coincidental correctness which means test cases exercise faulty statements but do not result in failure information. Recent researches indicate that coincidental correctness is a common problem in software testing and harmful for fault localization. To enhance effectiveness of fault localization, in this study, we present a clustering approach to identify coincidental correctness in test suites for fault localization. An effective clustering technique is used to group test cases. Then we present an adaptive sampling strategy to identify and choose potential coincidentally correct tests from clusters such that the number of the identified coincidentally correct tests is guaranteed to be no more than the actual number of coincidentally correct tests in the test suite. Three representative fault localization techniques are evaluated to see whether they can benefit from identified coincidentally correct tests. The experimental results show that our approach can alleviate the coincidental correctness problem and improve the effectiveness of fault localization.