diff --git a/toolkit/content/widgets/autocomplete.xml b/toolkit/content/widgets/autocomplete.xml
index fe1527d5f63..352eb66b287 100644
--- a/toolkit/content/widgets/autocomplete.xml
+++ b/toolkit/content/widgets/autocomplete.xml
@@ -308,8 +308,12 @@
 
       <method name="detachController">
         <body><![CDATA[
-          if (this.mController.input == this)
+          try { 
+            if  (this.mController.input == this)
             this.mController.input = null;
+          } catch (ex) {
+            // nothing really to do.
+          }       
         ]]></body>
       </method>
 
