diff --git a/Pipfile b/Pipfile
index 86960c586..ff075d9c1 100644
--- a/Pipfile
+++ b/Pipfile
@@ -11,7 +11,10 @@ flake8 = "*"
 setuptools = ">=30.3.0"
 setuptools-scm = "*"
 wheel = "*"
-autopep8 = "*"
+# The last flake8 version that supports Python 3.6 specifies "pycodestyle >=
+# 2.9.0, < 2.10.0". ref: https://github.com/PyCQA/flake8/pull/1633
+# The latest autopep8 specifies "pycodestyle >= 2.10.0". This conflict cannot be resolved. Pin the version to resolve this.
+autopep8 = "<=1.5.7"
 importlib-metadata = "<5.0"
 isort = "*"
 more_itertools = "<8.6"