diff --git a/pytorch3d/implicitron/tools/video_writer.py b/pytorch3d/implicitron/tools/video_writer.py
index 364dabee..7d5edd44 100644
--- a/pytorch3d/implicitron/tools/video_writer.py
+++ b/pytorch3d/implicitron/tools/video_writer.py
@@ -84,6 +84,8 @@ class VideoWriter:
                 or a 2-tuple defining the size of the output image.
         """
 
+        # pyre-fixme[6]: For 1st param expected `Union[PathLike[str], str]` but got
+        #  `Optional[str]`.
         outfile = os.path.join(self.cache_dir, self.regexp % self.frame_num)
 
         if isinstance(frame, matplotlib.figure.Figure):
@@ -125,6 +127,8 @@ class VideoWriter:
             video_path: The path to the generated video.
         """
 
+        # pyre-fixme[6]: For 1st param expected `Union[PathLike[str], str]` but got
+        #  `Optional[str]`.
         regexp = os.path.join(self.cache_dir, self.regexp)
 
         if self.output_format == "visdom":  # works for ppt too
diff --git a/pytorch3d/io/obj_io.py b/pytorch3d/io/obj_io.py
index ca6faf41..09bb5346 100644
--- a/pytorch3d/io/obj_io.py
+++ b/pytorch3d/io/obj_io.py
@@ -216,6 +216,8 @@ def load_obj(
     """
     data_dir = "./"
     if isinstance(f, (str, bytes, Path)):
+        # pyre-fixme[6]: For 1st param expected `PathLike[Variable[AnyStr <: [str,
+        #  bytes]]]` but got `Union[Path, bytes, str]`.
         data_dir = os.path.dirname(f)
     if path_manager is None:
         path_manager = PathManager()