diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 36bc184cc3..b6b309d838 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -2313,12 +2313,16 @@
       </optional>
       <optional>
         <element name="backend">
+          <optional>
            <attribute name='tap'>
              <ref name='absFilePath'/>
            </attribute>
+          </optional>
+          <optional>
            <attribute name='vhost'>
              <ref name='absFilePath'/>
            </attribute>
+          </optional>
         </element>
       </optional>
       <optional>