diff --git a/tests/cases/middleware.py b/tests/cases/middleware.py
index 18c68a31..184829b4 100644
--- a/tests/cases/middleware.py
+++ b/tests/cases/middleware.py
@@ -13,7 +13,8 @@
 
 
 class _State(base.BaseState):
-    hook_list: list[str] = []
+    def __init__(self) -> None:
+        self.hook_list: list[str] = []
 
 
 def create(