diff --git a/src/flake8_pydantic/visitor.py b/src/flake8_pydantic/visitor.py
index 65bfe0f..b3e2107 100644
--- a/src/flake8_pydantic/visitor.py
+++ b/src/flake8_pydantic/visitor.py
@@ -28,7 +28,9 @@ def leave_class(self) -> None:
         self.class_stack.pop()
 
     @property
-    def current_class(self) -> ClassType:
+    def current_class(self) -> ClassType | None:
+        if not self.class_stack:
+            return None
         return self.class_stack[-1]
 
     def _check_pyd_001(self, node: ast.AnnAssign) -> None: