diff --git a/xpfe/components/sidebar/resources/sidebarOverlay.xul b/xpfe/components/sidebar/resources/sidebarOverlay.xul
index 9359c44a1201..f7df93de703e 100644
--- a/xpfe/components/sidebar/resources/sidebarOverlay.xul
+++ b/xpfe/components/sidebar/resources/sidebarOverlay.xul
@@ -56,7 +56,7 @@
           </rule>
         </template>
       </box>
-      <html:iframe id="sidebar-content" content="true" src="about:blank" 
+      <html:iframe id="sidebar-content" type="content" src="about:blank" 
         class="panel-frame" flex='1*'/>
       <box id="sidebar-panels-bottom" align="vertical"
         datasources="chrome://sidebar/content/local-panels.rdf chrome://sidebar/content/remote-panels.rdf">