diff --git a/src/quart/app.py b/src/quart/app.py
index da23382..a55bfcf 100644
--- a/src/quart/app.py
+++ b/src/quart/app.py
@@ -29,6 +29,7 @@
 from aiofiles import open as async_open
 from aiofiles.base import AiofilesContextManager
 from aiofiles.threadpool.binary import AsyncBufferedReader
+import flask.app
 from flask.sansio.app import App
 from flask.sansio.scaffold import setupmethod
 from hypercorn.asyncio import serve
@@ -227,6 +228,9 @@ class Quart(App):
     websocket_class = Websocket
 
     default_config = ImmutableDict(
+
+        flask.app.Flask.default_config |
+
         {
             "APPLICATION_ROOT": "/",
             "BACKGROUND_TASK_SHUTDOWN_TIMEOUT": 5,  # Second