Thank you for your reply. I totally agree with you that since i can run the whole test suite with no issues using gradle (something that i'm already used to do all the times regardless of this specific problem now) this is just a minor problem. not to mention the fact I can stll use intellij/AS to run individual tests. It's just weird and a bit annoying that intellij/AS picks up automatically junit5 even though i'm only using junit4, i have no dependency from junit5 in my classpath and i'm just importing the junit4 kotlintest runner. I've posted the question because i was not so sure whether there was some settings of the IDE that I was missing. Thanks