--- a/mozilla-tests/b2g_config.py
+++ b/mozilla-tests/b2g_config.py
@@ -1498,17 +1498,17 @@ PLATFORM_UNITTEST_VARS = {
         'unittest-env': {
             "MOZ_NO_REMOTE": '1',
             "NO_EM_RESTART": '1',
             "XPCOM_DEBUG_BREAK": 'warn',
             "MOZ_CRASHREPORTER_NO_REPORT": '1',
             # for extracting dmg's
             "PAGER": '/bin/cat',
         },
-        'enable_opt_unittests': True,
+        'enable_opt_unittests': False,
         'enable_debug_unittests': False,
         'mountainlion-b2gdt': {
             'opt_unittest_suites': [],
             'debug_unittest_suites': [],
             'suite_config': {
                 'gaia-integration': {
                     'extra_args': [
                         '--cfg', 'b2g/gaia_integration_config.py',