diff --git a/examples/wifi_phy_hier.grc b/examples/wifi_phy_hier.grc
index 9ce5767..a3f1fd0 100644
--- a/examples/wifi_phy_hier.grc
+++ b/examples/wifi_phy_hier.grc
@@ -1566,7 +1566,7 @@
     </param>
     <param>
       <key>optional</key>
-      <value>False</value>
+      <value>True</value>
     </param>
     <param>
       <key>vlen</key>