1 files changed, 1 insertions, 1 deletions
diff --git a/tests/http/server/_base.py b/tests/http/server/_base.py
index 5071f83574..36472e57a8 100644
--- a/tests/http/server/_base.py
+++ b/tests/http/server/_base.py
@@ -556,6 +556,6 @@ def _get_stack_frame_method_name(frame_info: inspect.FrameInfo) -> str:
     return method_name
 
 
-def _hash_stack(stack: List[inspect.FrameInfo]):
+def _hash_stack(stack: List[inspect.FrameInfo]) -> Tuple[str, ...]:
     """Turns a stack into a hashable value that can be put into a set."""
     return tuple(_format_stack_frame(frame) for frame in stack)