diff --git a/aiohttp/client.py b/aiohttp/client.py
index 24f4222aeef..548b9e8fe49 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -325,7 +325,7 @@ def __init_subclass__(cls: Type["ClientSession"]) -> None:
         )
 
     def __del__(self, _warnings: Any = warnings) -> None:
-        if not hasattr(self, 'closed'):
+        if not hasattr(self, "closed"):
             # has not been initialized, nothing to do
             return