diff --git a/static/opensearchdescription.xml b/static/opensearchdescription.xml
index 709beaa7f..47fd790b5 100644
--- a/static/opensearchdescription.xml
+++ b/static/opensearchdescription.xml
@@ -4,6 +4,7 @@
   <Description>Search zim files in the catalog.</Description>
   <Url type="application/atom+xml;profile=opds-catalog"
        xmlns:atom="http://www.w3.org/2005/Atom"
+       xmlns:k="http://kiwix.org/opensearchextension/1.0"
        indexOffset="0"
-       template="/{{root}}/catalog/search?q={searchTerms}&lang={language}&count={count}&start={startIndex}"/>
+       template="/{{root}}/catalog/search?q={searchTerms?}&lang={language?}&name={k:name?}&tag={k:tag?}&notag={k:notag?}&maxsize={k:maxsize?}&count={count?}&start={startIndex?}"/>
 </OpenSearchDescription>