Index: /applications/editors/josm/plugins/build-common.xml
===================================================================
--- /applications/editors/josm/plugins/build-common.xml	(revision 34365)
+++ /applications/editors/josm/plugins/build-common.xml	(revision 34366)
@@ -249,4 +249,6 @@
             <bottom><![CDATA[<a href="https://josm.openstreetmap.de/wiki/Plugins">JOSM Plugins</a>]]></bottom>
             <arg value="-html5" if:set="isJava9" />
+            <arg value="--add-modules" if:set="isJava9" unless:set="isJava11" />
+            <arg value="java.activation,java.se.ee" if:set="isJava9" unless:set="isJava11" />
             <arg value="--add-exports" if:set="isJava9" unless:set="noJavaFX" />
             <arg value="javafx.graphics/com.sun.javafx.application=ALL-UNNAMED" if:set="isJava9" unless:set="noJavaFX" />