diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index dd9f153336..7a42b8e005 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -6360,9 +6360,10 @@ qemu-kvm -net nic,model=? /dev/null
             <p>
               This backend type expects a non-blocking character device as
               input. The file name is specified as contents of the
-              <code>backend</code> element. When no file name is specified
-              the hypervisor default is used. For qemu, the default is
-              /dev/random
+              <code>backend</code> element. <span class='since'>Since 1.3.4</span>
+              any path is accepted. Before that /dev/random and /dev/hwrng were
+              the only accepted paths. When no file name is specified the hypervisor
+              default is used. For qemu, the default is /dev/random
             </p>
           </dd>
           <dt><code>egd</code></dt>