diff --git a/pytools/__init__.py b/pytools/__init__.py
index 7f88a5e95ce7a73dad339eb984a7baba23341051..0dc66224fa8a82de6b1706009edfef54551ff749 100644
--- a/pytools/__init__.py
+++ b/pytools/__init__.py
@@ -1049,7 +1049,7 @@ def partition2(iterable):
     return part_true, part_false
 
 
-def product(iterable):
+def product(iterable: Iterable[Any]) -> Any:
     from operator import mul
     return reduce(mul, iterable, 1)