--- a/toolkit/components/url-classifier/nsUrlClassifierHashCompleter.js
+++ b/toolkit/components/url-classifier/nsUrlClassifierHashCompleter.js
@@ -180,16 +180,18 @@ function HashCompleter() {
   // Whether we have been informed of a shutdown by the shutdown event.
   this._shuttingDown = false;
 
   // A map of gethash URLs to next gethash time in miliseconds
   this._nextGethashTimeMs = {};
 
   Services.obs.addObserver(this, "quit-application");
   Services.prefs.addObserver(PREF_DEBUG_ENABLED, this);
+
+  loggingEnabled = Services.prefs.getBoolPref(PREF_DEBUG_ENABLED);
 }
 
 HashCompleter.prototype = {
   classID: Components.ID("{9111de73-9322-4bfc-8b65-2b727f3e6ec8}"),
   QueryInterface: XPCOMUtils.generateQI([Ci.nsIUrlClassifierHashCompleter,
                                          Ci.nsIRunnable,
                                          Ci.nsIObserver,
                                          Ci.nsISupportsWeakReference,