@thomasnield I did two things. 1. Add the Kotlin Facet to each project (F4 on the project, Facets, +). 2. Go into Settings -> Compiler -> Kotlin Compiler and select Target JVM Version 1.8 instead of the default 1.8. I think both of these issues are due to some issue with the latest IDEA. It should have picked up those settings from the pom. Also, the project language level was 1.3 by default, which I see in IDEA when importing new projects all the time.