diff --git a/captum/attr/_core/feature_permutation.py b/captum/attr/_core/feature_permutation.py
index 0f5be9381..19287b6ec 100644
--- a/captum/attr/_core/feature_permutation.py
+++ b/captum/attr/_core/feature_permutation.py
@@ -74,10 +74,8 @@ class FeaturePermutation(FeatureAblation):
 
     def __init__(
         self,
-        # pyre-fixme[24]: Generic type `Callable` expects 2 type parameters.
-        forward_func: Callable,
-        # pyre-fixme[24]: Generic type `Callable` expects 2 type parameters.
-        perm_func: Callable = _permute_feature,
+        forward_func: Callable[..., Union[int, float, Tensor, Future[Tensor]]],
+        perm_func: Callable[[Tensor, Tensor], Tensor] = _permute_feature,
     ) -> None:
         r"""
         Args:
@@ -101,8 +99,7 @@ def attribute(  # type: ignore
         self,
         inputs: TensorOrTupleOfTensorsGeneric,
         target: TargetType = None,
-        # pyre-fixme[2]: Parameter annotation cannot be `Any`.
-        additional_forward_args: Any = None,
+        additional_forward_args: object = None,
         feature_mask: Union[None, TensorOrTupleOfTensorsGeneric] = None,
         perturbations_per_eval: int = 1,
         show_progress: bool = False,
@@ -283,8 +280,7 @@ def attribute_future(
         self,
         inputs: TensorOrTupleOfTensorsGeneric,
         target: TargetType = None,
-        # pyre-fixme[2]: Parameter annotation cannot be `Any`.
-        additional_forward_args: Any = None,
+        additional_forward_args: object = None,
         feature_mask: Union[None, TensorOrTupleOfTensorsGeneric] = None,
         perturbations_per_eval: int = 1,
         show_progress: bool = False,