diff --git a/setup.py b/setup.py
index 4527cf910..8ce3b93f6 100644
--- a/setup.py
+++ b/setup.py
@@ -154,6 +154,9 @@ setup(
             "baostock",
             "yahooquery",
             "beautifulsoup4",
+            # The 5.0.0 version of importlib-metadata removed the deprecated endpoint,
+            # which prevented flake8 from working properly, so we restricted the version of importlib-metadata.
+            "importlib-metadata<5.0.0",
             "tianshou",
             "gym>=0.24",  # If you do not put gym at the end, gym will degrade causing pytest results to fail.
         ],