diff --git a/webapp/src/main/webapp/templates/freemarker/lib/lib-meta-tags.ftl b/webapp/src/main/webapp/templates/freemarker/lib/lib-meta-tags.ftl
index 9887d09b..c1ac3085 100644
--- a/webapp/src/main/webapp/templates/freemarker/lib/lib-meta-tags.ftl
+++ b/webapp/src/main/webapp/templates/freemarker/lib/lib-meta-tags.ftl
@@ -1,6 +1,6 @@
 <#-- $This file is distributed under the terms of the license in /doc/license.txt$ -->
 
-<#macro addCitationMetaTag uri content>
+<#macro addCitationMetaTag uri="" content="">
     <#if metaTags?? && uri?? && content??>
         <#switch uri>
             <#case "http://vivoweb.org/ontology/core#Authorship">