--- build.xml.orig
+++ build.xml
@@ -333,9 +334,10 @@
   <target name="docs" depends="prepare, prepare-docs">
     <echo message="Building docs for ${parser.Name} ${parser.Version} ..." />
     <java fork="yes"
-          classpath="${java.class.path}:${doc.generator.package}:./tools/xalan.jar"
+          classpath="/usr/share/java/xerces.jar:${java.class.path}:${doc.generator.package}:/usr/share/java/xalan2.jar"
           classname="${doc.generator}"
           failOnError="yes">
+      <jvmarg value="-Djava.awt.headless=true"/>
       <arg value="targetDirectory=${build.docs}"/>
       <arg value="${build.dir}/xdocs/docs-book.xml"/>
       <arg value="${build.dir}/xdocs/style"/>