diff --git a/test/runner.py b/test/runner.py
index ce76aba756863..b6e2d566f81d2 100755
--- a/test/runner.py
+++ b/test/runner.py
@@ -477,7 +477,7 @@ def parse_args():
                       help='Command to launch web browser in which to run browser tests.')
   parser.add_argument('--headless', action='store_true',
                       help='Run browser tests in headless mode.', default=None)
-  parser.add_argument('--browser-auto-config', type=bool, default=True,
+  parser.add_argument('--browser-auto-config', action=argparse.BooleanOptionalAction, default=None,
                       help='Use the default CI browser configuration.')
   parser.add_argument('tests', nargs='*')
   parser.add_argument('--failfast', action='store_true')
@@ -496,7 +496,7 @@ def parse_args():
 
 def configure():
   common.EMTEST_BROWSER = os.getenv('EMTEST_BROWSER')
-  common.EMTEST_BROWSER_AUTO_CONFIG = os.getenv('EMTEST_BROWSER_AUTO_CONFIG')
+  common.EMTEST_BROWSER_AUTO_CONFIG = int(os.getenv('EMTEST_BROWSER_AUTO_CONFIG', '1'))
   common.EMTEST_HEADLESS = int(os.getenv('EMTEST_HEADLESS', '0'))
   common.EMTEST_DETECT_TEMPFILE_LEAKS = int(os.getenv('EMTEST_DETECT_TEMPFILE_LEAKS', '0'))
   common.EMTEST_ALL_ENGINES = int(os.getenv('EMTEST_ALL_ENGINES', '0'))