diff --git a/fastapi/applications.py b/fastapi/applications.py
index 160d663015a65..62fdfc38b9e4a 100644
--- a/fastapi/applications.py
+++ b/fastapi/applications.py
@@ -87,7 +87,7 @@ def __init__(
         ),
         **extra: Any,
     ) -> None:
-        self._debug: bool = debug
+        self.debug: bool = debug
         self.title = title
         self.description = description
         self.version = version