--- a/perl_lib/EPrints/DataObj/EPrint.pm
+++ b/perl_lib/EPrints/DataObj/EPrint.pm
@@ -1911,7 +1911,7 @@ sub render_version_thread
                while( $clevel < $level )
                {
                        ++$clevel;
-                       $ul = $ul->lastChild->appendChild( $session->make_element( "ul" ) );
+                       $ul = $ul->getLastChild->appendChild( $session->make_element( "ul" ) );
                }
                # move up a level
                while( $clevel > $level )