diff --git a/sync_chromium.py b/sync_chromium.py
index 0a63f42..e5ec7c7 100755
--- a/sync_chromium.py
+++ b/sync_chromium.py
@@ -53,8 +53,11 @@
   env['GYP_CHROMIUM_NO_ACTION'] = '1'
   gclient_cmd = 'gclient.bat' if sys.platform.startswith('win') else 'gclient'
   args = [
-      gclient_cmd, 'sync', '--no-history', '--force', '--verbose', '--revision',
+      gclient_cmd, 'sync', '--no-history', '--force', '--revision',
       'src@'+opts.target_revision]
+  if os.environ.get('CHROME_HEADLESS') == '1':
+    args.append('-vvv')
+
   target_os_list = get_target_os_list()
   if target_os_list:
     args += ['--deps=' + target_os_list]