When changes in requirements occur, their associated tests must be adapted accordingly in order to maintain the quality of the evolving system. In practice, inconsistencies in requirements and acceptance tests—together with poor communication of changes—lead to software quality problems, unintended costs and project delays. We are developing GuideGen, a tool that helps requirements engineers, testers and other involved parties keep requirements and acceptance tests aligned. When requirements change, GuideGen analyzes the changes, automatically generates guidance on how to adapt the affected acceptance tests, and sends this information to subscribed parties. GuideGen also flags all non-aligned acceptance tests, thus keeping stakeholders aware of mismatches between requirements and acceptance tests. We evaluated GuideGen with data from three companies. For 262non-trivial changes of requirements, the suggestions generated by GuideGen were correct in more than 80 percent of the cases for agile requirements and about 67 percent for traditional ones. Demo video: https://vimeo.com/254865530