diff --git a/setup.py b/setup.py
index 4f9ad36..0ffc47c 100755
--- a/setup.py
+++ b/setup.py
@@ -31,7 +31,7 @@ deps = [
     'urllib3>=1.23',
     'requests>=2.0.1',
     'PySocks>=1.6.8',
-    'cryptography>=2.3',
+    'cryptography>=2.3,<=39.0.0',
     'idna==2.10',
     'PyYAML>=5.1',
     'cachetools',