--- a/addon-sdk/mach_commands.py
+++ b/addon-sdk/mach_commands.py
@@ -50,17 +50,17 @@ class MachCommands(MachCommandBase):
         for path, dirs, files in os.walk(js_src_dir):
             js_files = [f for f in files if f.endswith(('.js', '.jsm'))]
             if not js_files:
                 continue
 
             relative = mozpath.relpath(path, js_src_dir)
             dirs_to_files[relative] = js_files
 
-        moz_build = """# AUTOMATICALLY GENERATED FROM moz.build.in AND mach.  DO NOT EDIT.
+        moz_build = """# AUTOMATICALLY GENERATED FROM mozbuild.template AND mach.  DO NOT EDIT.
 # 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/.
 
 %(moz-build-template)s
 if CONFIG['MOZ_WIDGET_TOOLKIT'] != "gonk":
 %(non-b2g-modules)s
 %(always-on-modules)s"""

--- a/addon-sdk/mozbuild.template
+++ b/addon-sdk/mozbuild.template
@@ -3,13 +3,16 @@
 # 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/.
 
 BROWSER_CHROME_MANIFESTS += ['test/browser.ini']
 JETPACK_PACKAGE_MANIFESTS += ['source/test/jetpack-package.ini']
 JETPACK_ADDON_MANIFESTS += ['source/test/addons/jetpack-addon.ini']
 
-DIRS += ["source/modules/system"]
-
 EXTRA_JS_MODULES.sdk += [
     'source/app-extension/bootstrap.js',
 ]
+
+EXTRA_JS_MODULES.sdk.system += [
+    'source/modules/system/Startup.js',
+    'source/modules/system/XulApp.js',
+]