diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 6d265f3c2c71b06799fe78eaabec52b05fbf19d6..b34526fcbba40793975dd831e2a7b1d591d4fa61 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -1186,6 +1186,11 @@
         </choice>
         </attribute>
       </optional>
+      <optional>
+        <element name='readonly'>
+          <empty/>
+        </element>
+      </optional>
     </element>
   </define>
   <define name="filesystemtgt">