diff --git a/tests/cli/test_webapp.py b/tests/cli/test_webapp.py
index eaa1f6a..2688912 100644
--- a/tests/cli/test_webapp.py
+++ b/tests/cli/test_webapp.py
@@ -89,7 +89,7 @@ app.spec = wuttaweb.app:make_wsgi_app
                                                 reload_dirs=None,
                                                 factory=False,
                                                 interface='auto',
-                                                root_path=None)
+                                                root_path='')
 
         # with reload
         uvicorn.run.reset_mock()
@@ -103,4 +103,4 @@ app.spec = wuttaweb.app:make_wsgi_app
                                                 reload_dirs=None,
                                                 factory=False,
                                                 interface='auto',
-                                                root_path=None)
+                                                root_path='')