diff --git a/detectron2/utils/events.py b/detectron2/utils/events.py
index c4f9dadfd8..8a470c8ab2 100644
--- a/detectron2/utils/events.py
+++ b/detectron2/utils/events.py
@@ -3,14 +3,19 @@
 import json
 import logging
 import os
+import sys
 import time
 from collections import defaultdict
 from contextlib import contextmanager
-from functools import cached_property
 from typing import Optional
 import torch
 from fvcore.common.history_buffer import HistoryBuffer
 
+if sys.version_info >= (3, 8):
+    from functools import cached_property
+else:
+    from backports.cached_property import cached_property
+
 from detectron2.utils.file_io import PathManager
 
 __all__ = [
diff --git a/docs/requirements.txt b/docs/requirements.txt
index 720a1b1193..e6d5da0f85 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -21,3 +21,4 @@ omegaconf>=2.1.0.dev24
 hydra-core>=1.1.0.dev5
 scipy
 timm
+backports.cached-property==1.0.2; python_version < '3.8'
diff --git a/setup.py b/setup.py
index b51307a625..c118b06795 100644
--- a/setup.py
+++ b/setup.py
@@ -190,6 +190,7 @@ def get_model_zoo_configs() -> List[str]:
         "hydra-core>=1.1",
         "black",
         "packaging",
+        "backports.cached-property==1.0.2; python_version < '3.8'",
         # NOTE: When adding new dependencies, if it is required at import time (in addition
         # to runtime), it probably needs to appear in docs/requirements.txt, or as a mock
         # in docs/conf.py