diff --git a/torchtnt/utils/nan.py b/torchtnt/utils/nan.py
index a13d86e952..0840b64b8f 100644
--- a/torchtnt/utils/nan.py
+++ b/torchtnt/utils/nan.py
@@ -4,6 +4,8 @@
 # This source code is licensed under the BSD-style license found in the
 # LICENSE file in the root directory of this source tree.
 
+# pyre-strict
+
 from collections import deque
 from typing import Callable, Iterator, List, Optional, Sequence, Union