diff --git a/setup.py b/setup.py
index 619c740..c784f28 100644
--- a/setup.py
+++ b/setup.py
@@ -35,10 +35,10 @@
       install_requires=[
           'attrs',
           'chardet>=1.0.1',
-          'cryptography>=0.5',
-          'idna>=2.5',
+          'cryptography>=0.5,<3.3.3',
+          'idna>=2.5,<3.0',
           'ply>=3.10',
-          'regex>=0.1.20110315',
+          'regex>=0.1.20110315,<2022.1.18',
           'six',
           'tld',
           'WebOb>=0.9.8'],