diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 4b608855af..372aab73a3 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -3514,6 +3514,7 @@
           <choice>
             <value>/dev/random</value>
             <value>/dev/hwrng</value>
+            <empty/>
           </choice>
         </group>
         <group>