diff --git a/dom/interfaces/base/nsIContentPrefService.idl b/dom/interfaces/base/nsIContentPrefService.idl
index 3a2a997a5d8..0217c9831f9 100644
--- a/dom/interfaces/base/nsIContentPrefService.idl
+++ b/dom/interfaces/base/nsIContentPrefService.idl
@@ -71,7 +71,7 @@ interface nsIContentPrefCallback : nsISupports
   void onResult(in nsIVariant aResult);
 };
 
-[scriptable, uuid(36715960-de39-457b-9d02-b800d5d3079b)]
+[scriptable, uuid(0014e2b4-1bab-4946-9211-7d28fc8df4d7)]
 interface nsIContentPrefService : nsISupports
 {
   /**
@@ -131,6 +131,19 @@ interface nsIContentPrefService : nsISupports
    */
   boolean hasPref(in nsIVariant aGroup, in AString aName);
 
+  /**
+   * Check whether or not the value of a pref (or its non-existance) is cached.
+   *
+   * @param    aGroup      the group for which to check for the pref, as an nsIURI
+   *                       from which the hostname will be used, a string
+   *                       (typically in the format of a hostname), or null
+   *                       to check for the global pref (applies to all sites)
+   * @param    aName       the name of the pref to check for
+   * @throws   NS_ERROR_ILLEGAL_VALUE if aGroup is not a string, nsIURI, or null
+   * @throws   NS_ERROR_ILLEGAL_VALUE if aName is null or an empty string
+   */
+  boolean hasCachedPref(in nsIVariant aGroup, in AString aName);
+
   /**
    * Remove a pref.
    *
@@ -217,23 +230,6 @@ interface nsIContentPrefService : nsISupports
   readonly attribute mozIStorageConnection DBConnection;
 };
 
-[scriptable, uuid(126f07cb-edfe-497e-87dd-ba906506b287)]
-interface nsIContentPrefService_MOZILLA_2_0 : nsIContentPrefService
-{
-  /**
-   * Check whether or not the value of a pref (or its non-existance) is cached.
-   *
-   * @param    aGroup      the group for which to check for the pref, as an nsIURI
-   *                       from which the hostname will be used, a string
-   *                       (typically in the format of a hostname), or null
-   *                       to check for the global pref (applies to all sites)
-   * @param    aName       the name of the pref to check for
-   * @throws   NS_ERROR_ILLEGAL_VALUE if aGroup is not a string, nsIURI, or null
-   * @throws   NS_ERROR_ILLEGAL_VALUE if aName is null or an empty string
-   */
-  boolean hasCachedPref(in nsIVariant aGroup, in AString aName);
-};
-
 %{C++
 // The contractID for the generic implementation built in to xpcom.
 #define NS_CONTENT_PREF_SERVICE_CONTRACTID "@mozilla.org/content-pref/service;1"
diff --git a/toolkit/components/contentprefs/nsContentPrefService.js b/toolkit/components/contentprefs/nsContentPrefService.js
index 144a11633aa..a5f417ff171 100644
--- a/toolkit/components/contentprefs/nsContentPrefService.js
+++ b/toolkit/components/contentprefs/nsContentPrefService.js
@@ -143,7 +143,6 @@ ContentPrefService.prototype = {
 
   classID:          Components.ID("{e6a3f533-4ffa-4615-8eb4-d4e72d883fa7}"),
   QueryInterface:   XPCOMUtils.generateQI([Ci.nsIContentPrefService,
-                                           Ci.nsIContentPrefService_MOZILLA_2_0,
                                            Ci.nsIFrameMessageListener]),
 
 
diff --git a/toolkit/components/contentprefs/tests/unit/test_contentPrefsCache.js b/toolkit/components/contentprefs/tests/unit/test_contentPrefsCache.js
index 2b5fbd75d47..dd931c8f046 100644
--- a/toolkit/components/contentprefs/tests/unit/test_contentPrefsCache.js
+++ b/toolkit/components/contentprefs/tests/unit/test_contentPrefsCache.js
@@ -4,7 +4,7 @@
  */
 
 let cps = Cc["@mozilla.org/content-pref/service;1"].
-          getService(Ci.nsIContentPrefService_MOZILLA_2_0);
+          getService(Ci.nsIContentPrefService);
 
 function run_test() {
   testCacheWorks("test1.example.com", "test-pref1");
diff --git a/toolkit/content/Services.jsm b/toolkit/content/Services.jsm
index d96008a2be5..86ad255edd2 100644
--- a/toolkit/content/Services.jsm
+++ b/toolkit/content/Services.jsm
@@ -63,7 +63,7 @@ XPCOMUtils.defineLazyGetter(Services, "dirsvc", function () {
 
 XPCOMUtils.defineLazyServiceGetter(Services, "contentPrefs",
                                    "@mozilla.org/content-pref/service;1",
-                                   "nsIContentPrefService_MOZILLA_2_0");
+                                   "nsIContentPrefService");
 
 XPCOMUtils.defineLazyServiceGetter(Services, "wm",
                                    "@mozilla.org/appshell/window-mediator;1",