diff --git a/b2g/installer/package-manifest.in b/b2g/installer/package-manifest.in
index b5298c66eed..dbfb41b43e0 100644
--- a/b2g/installer/package-manifest.in
+++ b/b2g/installer/package-manifest.in
@@ -351,6 +351,8 @@
 @BINPATH@/components/BrowserElementParent.js
 @BINPATH@/components/ContactManager.js
 @BINPATH@/components/ContactManager.manifest
+@BINPATH@/components/NavigatorPropertyHelper.js
+@BINPATH@/components/NavigatorPropertyHelper.manifest
 @BINPATH@/components/PermissionSettings.js
 @BINPATH@/components/PermissionSettings.manifest
 @BINPATH@/components/PermissionPromptService.js
diff --git a/browser/installer/package-manifest.in b/browser/installer/package-manifest.in
index 938dea995a4..de18d5c1101 100644
--- a/browser/installer/package-manifest.in
+++ b/browser/installer/package-manifest.in
@@ -514,6 +514,8 @@
 @BINPATH@/components/PermissionSettings.manifest
 @BINPATH@/components/ContactManager.js
 @BINPATH@/components/ContactManager.manifest
+@BINPATH@/components/NavigatorPropteryHelper.js
+@BINPATH@/components/NavigatorPropertyHelper.manifest
 @BINPATH@/components/AlarmsManager.js
 @BINPATH@/components/AlarmsManager.manifest
 @BINPATH@/components/TCPSocket.js
diff --git a/dom/base/Makefile.in b/dom/base/Makefile.in
index b9b862b96b8..378705268a4 100644
--- a/dom/base/Makefile.in
+++ b/dom/base/Makefile.in
@@ -21,6 +21,8 @@ EXTRA_COMPONENTS = \
   SiteSpecificUserAgent.manifest \
   ConsoleAPI.js \
   ConsoleAPI.manifest \
+  NavigatorPropertyHelper.js \
+  NavigatorPropertyHelper.manifest \
   $(NULL)
 
 EXTRA_JS_MODULES = ConsoleAPIStorage.jsm \
diff --git a/dom/base/NavigatorPropertyHelper.js b/dom/base/NavigatorPropertyHelper.js
new file mode 100644
index 00000000000..8db334ddc9a
--- /dev/null
+++ b/dom/base/NavigatorPropertyHelper.js
@@ -0,0 +1,66 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const DEBUG = false;
+function debug(s) { dump("-*- NavigatorPropertyHelper: " + s + "\n"); }
+
+const Ci = Components.interfaces;
+const Cu = Components.utils;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+
+function NavigatorPropertyHelper() { };
+
+NavigatorPropertyHelper.prototype = {
+
+  classID : Components.ID("{f0d03420-a0ce-11e2-9e96-0800200c9a66}"),
+  QueryInterface : XPCOMUtils.generateQI([Ci.nsIObserver, Ci.nsISupportsWeakReference]),
+
+  observe: function observe(subject, topic, data) {
+    if (DEBUG) debug("topic: " + topic + ", data: " + data);
+    let cm = Components.classes["@mozilla.org/categorymanager;1"].getService(Ci.nsICategoryManager);
+    switch (topic) {
+      case 'app-startup':
+        let enumerator = cm.enumerateCategory("JavaScript-navigator-property-maybe");
+        while (enumerator.hasMoreElements()) {
+          let entry = enumerator.getNext().QueryInterface(Ci.nsISupportsCString);
+          let keyVal = cm.getCategoryEntry("JavaScript-navigator-property-maybe", entry).split(',');
+          try {
+            if (Services.prefs.getBoolPref(entry)) {
+              if (DEBUG) debug("enable: " + keyVal[0]);
+              cm.addCategoryEntry("JavaScript-navigator-property", keyVal[0], keyVal[1], false, false);
+            }
+          } catch (ex) {
+            if (DEBUG) debug("no pref found: " + entry);
+          }
+          Services.prefs.addObserver(entry, this, true);
+        }
+        break;
+      case 'nsPref:changed':
+        let keyVal = cm.getCategoryEntry("JavaScript-navigator-property-maybe", data).split(',');
+        let key = keyVal[0];
+        let val = keyVal[1];
+        try {
+          if (Services.prefs.getBoolPref(data)) {
+            if (DEBUG) debug("enable: " + key);
+            cm.addCategoryEntry("JavaScript-navigator-property", key, val, false, false);
+          } else {
+            if (DEBUG) debug("disable: " + key);
+            cm.deleteCategoryEntry("JavaScript-navigator-property", key, false);
+          }
+        } catch (ex) {
+          if (DEBUG) debug("no pref found: " + data);
+          cm.deleteCategoryEntry("JavaScript-navigator-property", key, false);
+        }
+        break;
+      default:
+        if (DEBUG) debug("unknown topic: " + topic);
+    }
+  },
+}
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([NavigatorPropertyHelper])
diff --git a/dom/base/NavigatorPropertyHelper.manifest b/dom/base/NavigatorPropertyHelper.manifest
new file mode 100644
index 00000000000..8d3c50e96a8
--- /dev/null
+++ b/dom/base/NavigatorPropertyHelper.manifest
@@ -0,0 +1,3 @@
+component {f0d03420-a0ce-11e2-9e96-0800200c9a66} NavigatorPropertyHelper.js
+contract @mozilla.org/navigatorPropertyHelper;1 {f0d03420-a0ce-11e2-9e96-0800200c9a66}
+category app-startup NavigatorPropertyHelper service,@mozilla.org/navigatorPropertyHelper;1
\ No newline at end of file
diff --git a/dom/contacts/ContactManager.js b/dom/contacts/ContactManager.js
index 28d54db45a5..c0ca8d16738 100644
--- a/dom/contacts/ContactManager.js
+++ b/dom/contacts/ContactManager.js
@@ -700,10 +700,6 @@ ContactManager.prototype = {
   },
 
   init: function(aWindow) {
-    // Set navigator.mozContacts to null.
-    if (!Services.prefs.getBoolPref("dom.mozContacts.enabled"))
-      return null;
-
     this.initHelper(aWindow, ["Contacts:Find:Return:OK", "Contacts:Find:Return:KO",
                               "Contacts:Clear:Return:OK", "Contacts:Clear:Return:KO",
                               "Contact:Save:Return:OK", "Contact:Save:Return:KO",
diff --git a/dom/contacts/ContactManager.manifest b/dom/contacts/ContactManager.manifest
index 6bbe3c5b33d..95226cc852f 100644
--- a/dom/contacts/ContactManager.manifest
+++ b/dom/contacts/ContactManager.manifest
@@ -22,4 +22,4 @@ category JavaScript-global-constructor mozContact @mozilla.org/contact;1
 
 component {1d70322b-f11b-4f19-9586-7bf291f212aa} ContactManager.js
 contract @mozilla.org/contactManager;1 {1d70322b-f11b-4f19-9586-7bf291f212aa}
-category JavaScript-navigator-property mozContacts @mozilla.org/contactManager;1
+category JavaScript-navigator-property-maybe dom.mozContacts.enabled mozContacts,@mozilla.org/contactManager;1
diff --git a/dom/contacts/tests/test_contacts_basics.html b/dom/contacts/tests/test_contacts_basics.html
index 7eeefe87fcd..5459ee8c340 100644
--- a/dom/contacts/tests/test_contacts_basics.html
+++ b/dom/contacts/tests/test_contacts_basics.html
@@ -228,11 +228,13 @@ function checkContacts(contact1, contact2) {
   }
 }
 
+function tests() {
+
 var req;
 var index = 0;
 
 var mozContacts = window.navigator.mozContacts;
-
+ok(mozContacts, "mozContacts exists");
 var steps = [
   function () {
     ok(true, "Deleting database");
@@ -1245,11 +1247,12 @@ function permissionTest() {
   }
 }
 
-var gContactsEnabled = SpecialPowers.getBoolPref("dom.mozContacts.enabled");
-SimpleTest.waitForExplicitFinish();
-addLoadEvent(permissionTest);
+permissionTest();
+};
 
-ok(true, "test passed");
+var gContactsEnabled = SpecialPowers.getBoolPref("dom.mozContacts.enabled");
+addLoadEvent(tests);
+SimpleTest.waitForExplicitFinish();
 </script>
 </pre>
 </body>
diff --git a/mobile/android/installer/package-manifest.in b/mobile/android/installer/package-manifest.in
index 231d8c5e795..d2fd884e9ed 100644
--- a/mobile/android/installer/package-manifest.in
+++ b/mobile/android/installer/package-manifest.in
@@ -261,6 +261,8 @@
 @BINPATH@/components/ConsoleAPI.js
 @BINPATH@/components/ContactManager.js
 @BINPATH@/components/ContactManager.manifest
+@BINPATH@/components/NavigatorPropteryHelper.js
+@BINPATH@/components/NavigatorPropertyHelper.manifest
 @BINPATH@/components/SettingsManager.js
 @BINPATH@/components/SettingsManager.manifest
 @BINPATH@/components/SettingsService.js