Index: trunk/build.xml
===================================================================
--- trunk/build.xml	(revision 13492)
+++ trunk/build.xml	(revision 13494)
@@ -384,5 +384,5 @@
             <doctitle><![CDATA[<h2>JOSM - Javadoc</h2>]]></doctitle>
             <bottom><![CDATA[<a href="https://josm.openstreetmap.de/">JOSM</a>]]></bottom>
-            <arg value="-html4" if:set="isJava9" />
+            <arg value="-html5" if:set="isJava9" />
             <arg value="--add-exports" if:set="isJava9" />
             <arg value="java.base/sun.security.util=ALL-UNNAMED" if:set="isJava9" />