diff --git a/jupyterlab/commands.py b/jupyterlab/commands.py
index ff77c9a3da26..dc670e274a6d 100644
--- a/jupyterlab/commands.py
+++ b/jupyterlab/commands.py
@@ -302,6 +302,11 @@ def __init__(self, logger=None, core_config=None, **kwargs):
             kwargs['core_config'] = core_config
         if logger is not None:
             kwargs['logger'] = logger
+
+        # use the default if app_dir is empty
+        if 'app_dir' in kwargs and not kwargs['app_dir']:
+            kwargs.pop('app_dir')
+
         super(AppOptions, self).__init__(**kwargs)
 
     app_dir = Unicode(help='The application directory')