Index: trunk/build.xml
===================================================================
--- trunk/build.xml	(revision 12227)
+++ trunk/build.xml	(revision 12228)
@@ -442,4 +442,6 @@
                     <jvmarg value="--add-exports" if:set="isJava9" />
                     <jvmarg value="java.base/sun.security.x509=ALL-UNNAMED" if:set="isJava9" />
+                    <jvmarg value="--add-opens" if:set="isJava9" />
+                    <jvmarg value="java.base/java.lang=ALL-UNNAMED" if:set="isJava9" />
                     <sysproperty key="josm.home" value="${test.dir}/config/@{testfamily}-josm.home"/>
                     <sysproperty key="josm.test.data" value="${test.dir}/data"/>