diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index f1609f90f5..3106510ad0 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -5531,6 +5531,9 @@
           </choice>
         </attribute>
       </optional>
+      <optional>
+        <ref name="alias"/>
+      </optional>
       <optional>
         <ref name="address"/>
       </optional>