diff --git a/docs/reference/gdk/gdk-docs.sgml b/docs/reference/gdk/gdk-docs.sgml
index ab865ec143..1e0c7b51bc 100644
--- a/docs/reference/gdk/gdk-docs.sgml
+++ b/docs/reference/gdk/gdk-docs.sgml
@@ -108,6 +108,10 @@
     <title>Index of new symbols in 2.18</title>
     <xi:include href="xml/api-index-2.18.xml"><xi:fallback /></xi:include>
   </index>
+  <index id="api-index-2-20" role="2.20">
+    <title>Index of new symbols in 2.20</title>
+    <xi:include href="xml/api-index-2.20.xml"><xi:fallback /></xi:include>
+  </index>
 
   <xi:include href="xml/annotation-glossary.xml"><xi:fallback /></xi:include>