diff --git a/docs/reference/gtk/gtk-docs.sgml b/docs/reference/gtk/gtk-docs.sgml
index 35008048a8..ff9f1519c4 100644
--- a/docs/reference/gtk/gtk-docs.sgml
+++ b/docs/reference/gtk/gtk-docs.sgml
@@ -428,6 +428,10 @@
     <title>Index of new symbols in 3.10</title>
     <xi:include href="xml/api-index-3.10.xml"><xi:fallback /></xi:include>
   </index>
+  <index id="api-index-3-12" role="3.12">
+    <title>Index of new symbols in 3.12</title>
+    <xi:include href="xml/api-index-3.12.xml"><xi:fallback /></xi:include>
+  </index>
 
   <xi:include href="xml/annotation-glossary.xml"><xi:fallback /></xi:include>