Westermo Research and Development has developed SuiteBuilder, an automated tool to determine an effective ordering of regression test cases. The ordering is based on factors such as fault detection success, the interval since the last execution, and code modifications. SuiteBuilder has enabled Westermo to overcome numerous regression-testing problems, including lack of time to run a complete regression suite, failure to detect bugs in a timely manner, and repeatedly omitted tests. In the tool's first two years of use, reordered test suites finished in the available time, most fault-detecting test cases were located in the first third of suites, no important test case was omitted, and the necessity for manual work on the suites decreased greatly.