--- a/toolkit/mozapps/extensions/addonManager.js
+++ b/toolkit/mozapps/extensions/addonManager.js
@@ -7,18 +7,16 @@
  * It is responsible for initializing and shutting down the AddonManager as well
  * as passing new installs from webpages to the AddonManager.
  */
 
 "use strict";
 
 const { classes: Cc, interfaces: Ci, utils: Cu, results: Cr } = Components;
 
-const PREF_EM_UPDATE_INTERVAL = "extensions.update.interval";
-
 // The old XPInstall error codes
 const EXECUTION_ERROR   = -203;
 const CANT_READ_ARCHIVE = -207;
 const USER_CANCELLED    = -210;
 const DOWNLOAD_ERROR    = -228;
 const UNSUPPORTED_TYPE  = -244;
 const SUCCESS           = 0;