diff --git a/docs/schemas/capability.rng b/docs/schemas/capability.rng
index dbfe1c5093..a9daa409c5 100644
--- a/docs/schemas/capability.rng
+++ b/docs/schemas/capability.rng
@@ -224,9 +224,9 @@
       <optional>
 	<ref name='emulator'/>
       </optional>
-      <optional>
+      <zeroOrMore>
 	<ref name='machine'/>
-      </optional>
+      </zeroOrMore>
     </element>
   </define>