diff --git a/src/prefect/tasks.py b/src/prefect/tasks.py
index c5331d10149a..c5406852e58c 100644
--- a/src/prefect/tasks.py
+++ b/src/prefect/tasks.py
@@ -187,7 +187,7 @@ def _infer_parent_task_runs(
     return parents
 
 
-def _generate_task_key(fn: Callable) -> str:
+def _generate_task_key(fn: Callable[..., Any]) -> str:
     """Generate a task key based on the function name and source code.
 
     We may eventually want some sort of top-level namespace here to