diff --git a/setup.py b/setup.py
index 73d0f71..4e87a72 100644
--- a/setup.py
+++ b/setup.py
@@ -19,9 +19,9 @@
 
 
 DEPENDENCIES = (
-    'cachetools>=2.0.0',
+    'cachetools>=2.0.0,<3.0',
     'pyasn1-modules>=0.2.1',
-    'rsa>=3.1.4',
+    'rsa>=3.1.4,<4.0',
     'setuptools>=40.3.0',
     'six>=1.9.0',
 )