diff --git a/addon-sdk/source/test/test-l10n-locale.js b/addon-sdk/source/test/test-l10n-locale.js
index 564abbf1be6f..dba64d2d52e0 100644
--- a/addon-sdk/source/test/test-l10n-locale.js
+++ b/addon-sdk/source/test/test-l10n-locale.js
@@ -110,8 +110,7 @@ exports.testPreferedOsLocale = function(assert) {
   prefs.set(PREF_SELECTED_LOCALE, "");
   prefs.set(PREF_ACCEPT_LANGUAGES, "");
 
-  let expectedLocale = Services.locale.getLocaleComponentForUserAgent().
-    toLowerCase();
+  let expectedLocale = Services.locale.getAppLocale().toLowerCase();
   let expectedLocaleList = [expectedLocale];
 
   // Add default "en-us" fallback if the main language is not already en-us
diff --git a/browser/modules/DirectoryLinksProvider.jsm b/browser/modules/DirectoryLinksProvider.jsm
index 5fe9f9fce06f..d9f44e82dee7 100644
--- a/browser/modules/DirectoryLinksProvider.jsm
+++ b/browser/modules/DirectoryLinksProvider.jsm
@@ -194,7 +194,8 @@ var DirectoryLinksProvider = {
     } catch (e) {}
 
     if (matchOS) {
-      return Services.locale.getLocaleComponentForUserAgent();
+      return Cc["@mozilla.org/intl/ospreferences;1"].
+             getService(Ci.mozIOSPreferences).getSystemLocale();
     }
 
     try {
diff --git a/toolkit/components/telemetry/TelemetryEnvironment.jsm b/toolkit/components/telemetry/TelemetryEnvironment.jsm
index fdaf93fa69a8..9d0e737b300b 100644
--- a/toolkit/components/telemetry/TelemetryEnvironment.jsm
+++ b/toolkit/components/telemetry/TelemetryEnvironment.jsm
@@ -230,9 +230,7 @@ function enforceBoolean(aValue) {
  */
 function getBrowserLocale() {
   try {
-    return Cc["@mozilla.org/chrome/chrome-registry;1"].
-             getService(Ci.nsIXULChromeRegistry).
-             getSelectedLocale("global");
+    return Services.locale.getAppLocale();
   } catch (e) {
     return null;
   }
@@ -244,7 +242,9 @@ function getBrowserLocale() {
  */
 function getSystemLocale() {
   try {
-    return Services.locale.getLocaleComponentForUserAgent();
+    return Cc["@mozilla.org/intl/ospreferences;1"].
+             getService(Ci.mozIOSPreferences).
+             getSystemLocale();
   } catch (e) {
     return null;
   }
diff --git a/toolkit/modules/Locale.jsm b/toolkit/modules/Locale.jsm
index fab39df0abb3..1066835cc639 100644
--- a/toolkit/modules/Locale.jsm
+++ b/toolkit/modules/Locale.jsm
@@ -18,8 +18,11 @@ this.Locale = {
    * @return  the selected locale or "en-US" if none is selected
    */
   getLocale() {
-    if (Preferences.get(PREF_MATCH_OS_LOCALE, false))
-      return Services.locale.getLocaleComponentForUserAgent();
+    if (Preferences.get(PREF_MATCH_OS_LOCALE, false)) {
+      const osPrefs =
+        Cc["@mozilla.org/intl/ospreferences;1"].getService(Ci.mozIOSPreferences);
+      return osPrefs.getSystemLocale();
+    }
     try {
       let locale = Preferences.get(PREF_SELECTED_LOCALE, null, Ci.nsIPrefLocalizedString);
       if (locale)
diff --git a/toolkit/modules/Services.jsm b/toolkit/modules/Services.jsm
index 759427052d47..a9e7b719e30c 100644
--- a/toolkit/modules/Services.jsm
+++ b/toolkit/modules/Services.jsm
@@ -75,7 +75,7 @@ var initTable = [
   ["els", "@mozilla.org/eventlistenerservice;1", "nsIEventListenerService"],
   ["eTLD", "@mozilla.org/network/effective-tld-service;1", "nsIEffectiveTLDService"],
   ["io", "@mozilla.org/network/io-service;1", "nsIIOService2"],
-  ["locale", "@mozilla.org/intl/nslocaleservice;1", "nsILocaleService"],
+  ["locale", "@mozilla.org/intl/localeservice;1", "mozILocaleService"],
   ["logins", "@mozilla.org/login-manager;1", "nsILoginManager"],
   ["obs", "@mozilla.org/observer-service;1", "nsIObserverService"],
   ["perms", "@mozilla.org/permissionmanager;1", "nsIPermissionManager"],
diff --git a/toolkit/modules/tests/xpcshell/test_Services.js b/toolkit/modules/tests/xpcshell/test_Services.js
index 81b8757cb0cd..325d6cb42c50 100644
--- a/toolkit/modules/tests/xpcshell/test_Services.js
+++ b/toolkit/modules/tests/xpcshell/test_Services.js
@@ -45,7 +45,7 @@ function run_test() {
   checkService("focus", Ci.nsIFocusManager);
   checkService("io", Ci.nsIIOService);
   checkService("io", Ci.nsIIOService2);
-  checkService("locale", Ci.nsILocaleService);
+  checkService("locale", Ci.mozILocaleService);
   checkService("logins", Ci.nsILoginManager);
   checkService("obs", Ci.nsIObserverService);
   checkService("perms", Ci.nsIPermissionManager);
diff --git a/toolkit/mozapps/extensions/AddonManager.jsm b/toolkit/mozapps/extensions/AddonManager.jsm
index 21d4b40a161a..dd50c1b6590d 100644
--- a/toolkit/mozapps/extensions/AddonManager.jsm
+++ b/toolkit/mozapps/extensions/AddonManager.jsm
@@ -329,8 +329,11 @@ function promiseCallProvider(aProvider, aMethod, ...aArgs) {
  */
 function getLocale() {
   try {
-    if (Services.prefs.getBoolPref(PREF_MATCH_OS_LOCALE))
-      return Services.locale.getLocaleComponentForUserAgent();
+    if (Services.prefs.getBoolPref(PREF_MATCH_OS_LOCALE)) {
+      const osPrefs =
+        Cc["@mozilla.org/intl/ospreferences;1"].getService(Ci.mozIOSPreferences);
+      return osPrefs.getSystemLocale();
+    }
   } catch (e) { }
 
   try {