diff --git a/pytato/array.py b/pytato/array.py
index 0f9fc5db1d31ebc4d46dd3ba29597dd6fd154de0..52a728346d6ea947e1eda5d8a96142f8172ac985 100644
--- a/pytato/array.py
+++ b/pytato/array.py
@@ -526,7 +526,7 @@ class Array(Taggable):
     __rmatmul__ = partialmethod(__matmul__, reverse=True)
 
     def _binary_op(self,
-            op: Any,
+            op: Callable[[ScalarExpression, ScalarExpression], ScalarExpression],
             other: ArrayOrScalar,
             get_result_type: Callable[[DtypeOrScalar, DtypeOrScalar], np.dtype[Any]] = _np_result_type,  # noqa
             reverse: bool = False) -> Array: