diff --git a/toolkit/components/url-classifier/content/listmanager.js b/toolkit/components/url-classifier/content/listmanager.js
index 018d53f2b82..079178fd88f 100644
--- a/toolkit/components/url-classifier/content/listmanager.js
+++ b/toolkit/components/url-classifier/content/listmanager.js
@@ -77,7 +77,7 @@ function PROT_ListManager() {
   this.tablesData = {};
 
   this.observerServiceObserver_ = new G_ObserverServiceObserver(
-                                          'xpcom-shutdown',
+                                          'quit-application',
                                           BindToObject(this.shutdown_, this),
                                           true /*only once*/);
 
@@ -119,6 +119,10 @@ function PROT_ListManager() {
  * Delete all of our data tables which seem to leak otherwise.
  */
 PROT_ListManager.prototype.shutdown_ = function() {
+  if (this.keyManager_) {
+    this.keyManager_.shutdown();
+  }
+
   for (var name in this.tablesData) {
     delete this.tablesData[name];
   }
diff --git a/toolkit/components/url-classifier/content/url-crypto-key-manager.js b/toolkit/components/url-classifier/content/url-crypto-key-manager.js
index 943319d0da1..5eb837cb2db 100644
--- a/toolkit/components/url-classifier/content/url-crypto-key-manager.js
+++ b/toolkit/components/url-classifier/content/url-crypto-key-manager.js
@@ -212,8 +212,8 @@ PROT_UrlCryptoKeyManager.prototype.reKey = function() {
   G_Debug(this, "Attempting to re-key");
   // If the keyUrl isn't set, we don't do anything.
   if (!this.testing_ && this.keyUrl_) {
-    (new PROT_XMLFetcher()).get(this.keyUrl_,
-                                BindToObject(this.onGetKeyResponse, this));
+    this.fetcher_ = new PROT_XMLFetcher();
+    this.fetcher_.get(this.keyUrl_, BindToObject(this.onGetKeyResponse, this));
     this.updating_ = true;
 
     // Calculate the next time we're allowed to re-key.
@@ -348,6 +348,7 @@ PROT_UrlCryptoKeyManager.prototype.onGetKeyResponse = function(responseText) {
   var wrappedKey = response[this.WRAPPED_KEY_NAME];
 
   this.updating_ = false;
+  this.fetcher_ = null;
 
   if (response && clientKey && wrappedKey) {
     G_Debug(this, "Got new key from: " + responseText);
@@ -418,6 +419,13 @@ PROT_UrlCryptoKeyManager.prototype.maybeLoadOldKey = function() {
   }
 }
 
+PROT_UrlCryptoKeyManager.prototype.shutdown = function() {
+  if (this.fetcher_) {
+    this.fetcher_.cancel();
+    this.fetcher_ = null;
+  }
+}
+
 
 #ifdef DEBUG
 /**
diff --git a/toolkit/components/url-classifier/content/xml-fetcher.js b/toolkit/components/url-classifier/content/xml-fetcher.js
index 08d837dcdb6..b79b851af2c 100644
--- a/toolkit/components/url-classifier/content/xml-fetcher.js
+++ b/toolkit/components/url-classifier/content/xml-fetcher.js
@@ -110,6 +110,11 @@ PROT_XMLFetcher.prototype = {
     this._request.send(null);
   },
 
+  cancel: function() {
+    this._request.onreadystatechange = null;
+    this._request.abort();
+  },
+
   /**
    * Called periodically by the request to indicate some state change. 4
    * means content has been received.