--- a/python/mozbuild/mozbuild/action/langpack_manifest.py
+++ b/python/mozbuild/mozbuild/action/langpack_manifest.py
@@ -284,16 +284,40 @@ def parse_chrome_manifest(path, base_pat
                 'locale': entry.id,
                 'platforms': convert_entry_flags_to_platform_codes(entry.flags),
                 'path': mozpath.normsep(entry_path)
             })
         else:
             raise Exception('Unknown type {0}'.format(entry.name))
 
 
+##
+# Gets the version to use in the langpack.
+#
+# This uses the env variable MOZ_BUILD_DATE if it exists to expand the version to be unique
+# in automation.
+#
+# Args:
+#    min_version - Application version
+#
+# Returns:
+#    str - Version to use, may include buildid
+#
+###
+def get_version_maybe_buildid(min_version):
+    version = str(min_version)
+    buildid = os.environ.get('MOZ_BUILD_DATE')
+    if buildid and len(buildid) != 14:
+        print >>sys.stderr, 'Ignoring invalid MOZ_BUILD_DATE: %s' % buildid
+        buildid = None
+    if buildid:
+        version = version + "buildid" + buildid
+    return version
+
+
 ###
 # Generates a new web manifest dict with values specific for a language pack.
 #
 # Args:
 #    locstr         (str)  - A string with a comma separated list of locales
 #                            for which resources are embedded in the
 #                            language pack
 #    min_app_ver    (str)  - A minimum version of the application the language
@@ -370,17 +394,17 @@ def create_webmanifest(locstr, min_app_v
             'gecko': {
                 'id': 'langpack-{0}@firefox.mozilla.org'.format(main_locale),
                 'strict_min_version': min_app_ver,
                 'strict_max_version': max_app_ver,
             }
         },
         'name': '{0} Language Pack'.format(defines['MOZ_LANG_TITLE']),
         'description': 'Language pack for {0} for {1}'.format(app_name, main_locale),
-        'version': min_app_ver,
+        'version': get_version_maybe_buildid(min_app_ver),
         'languages': {},
         'sources': {
             'browser': {
                 'base_path': 'browser/'
             }
         },
         'author': author
     }