diff --git a/pytorch3d/datasets/r2n2/utils.py b/pytorch3d/datasets/r2n2/utils.py
index fa9c84d2..f2c96802 100644
--- a/pytorch3d/datasets/r2n2/utils.py
+++ b/pytorch3d/datasets/r2n2/utils.py
@@ -137,7 +137,9 @@ def compute_extrinsic_matrix(azimuth, elevation, distance):
     return RT
 
 
-def read_binvox_coords(f, integer_division=True, dtype=torch.float32):
+def read_binvox_coords(
+    f, integer_division: bool = True, dtype: torch.dtype = torch.float32
+):
     """
     Copied from meshrcnn codebase:
     https://github.com/facebookresearch/meshrcnn/blob/master/shapenet/utils/binvox_torch.py#L5
diff --git a/pytorch3d/io/ply_io.py b/pytorch3d/io/ply_io.py
index 73bbdd92..85ae1aa3 100644
--- a/pytorch3d/io/ply_io.py
+++ b/pytorch3d/io/ply_io.py
@@ -462,7 +462,7 @@ def _read_ply_element_ascii(f, definition: _PlyElementType):
     return data
 
 
-def _read_raw_array(f, aim: str, length: int, dtype=np.uint8, dtype_size=1):
+def _read_raw_array(f, aim: str, length: int, dtype: type = np.uint8, dtype_size=1):
     """
     Read [length] elements from a file.
 
diff --git a/pytorch3d/ops/sample_points_from_meshes.py b/pytorch3d/ops/sample_points_from_meshes.py
index afc573f6..58d3f26b 100644
--- a/pytorch3d/ops/sample_points_from_meshes.py
+++ b/pytorch3d/ops/sample_points_from_meshes.py
@@ -142,7 +142,7 @@ def sample_points_from_meshes(
 
 
 def _rand_barycentric_coords(
-    size1, size2, dtype, device
+    size1, size2, dtype: torch.dtype, device: torch.device
 ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
     """
     Helper function to generate random barycentric coordinates which are uniformly