diff --git a/sdk/python/packages/flet-core/src/flet_core/page.py b/sdk/python/packages/flet-core/src/flet_core/page.py
index 37708d841..0356b8a01 100644
--- a/sdk/python/packages/flet-core/src/flet_core/page.py
+++ b/sdk/python/packages/flet-core/src/flet_core/page.py
@@ -111,6 +111,7 @@ def __init__(self, conn: Connection, session_id):
         self.__offstage = Offstage()
         self.__theme = None
         self.__dark_theme = None
+        self.__theme_mode = ThemeMode.SYSTEM  # Default Theme Mode
         self.__pubsub = PubSub(conn.pubsubhub, session_id)
         self.__client_storage = ClientStorage(self)
         self.__session_storage = SessionStorage(self)