diff --git a/src/pyvmcon/problem.py b/src/pyvmcon/problem.py
index 92d9e67..599b7d5 100644
--- a/src/pyvmcon/problem.py
+++ b/src/pyvmcon/problem.py
@@ -146,7 +146,12 @@ def num_inequality(self) -> int:
 
     def __iter__(
         self,
-    ) -> Iterator[_ScalarReturnFunctionAlias | _VectorReturnFunctionAlias]:
+    ) -> Iterator[
+        _ScalarReturnFunctionAlias
+        | _VectorReturnFunctionAlias
+        | list[_ScalarReturnFunctionAlias]
+        | list[_VectorReturnFunctionAlias]
+    ]:
         """Convert the dataclass into an iterable.
 
         .. deprecated:: 2.4.2