Figured out a fix. Added this to my project.clj file: :jvm-opts ^:replace ["-Xmx1g" "-server" "--add-modules=java.xml.bind"] idk about the server and 1g but the modules was what fixed it as there’s a new modules system in jdk9. Got the other inspiration from lein new mies testmies project.clj. Other references http://stackoverflow.com/questions/43198538/adding-long-jvm-options-to-ant-launch-command and https://bugs.openjdk.java.net/browse/JDK-8157670