diff --git a/setup.py b/setup.py
index be3bfe7..9ebac0d 100644
--- a/setup.py
+++ b/setup.py
@@ -1,5 +1,6 @@
 import setuptools
 
+
 with open("README.md", "r", encoding="utf-8") as fh:
     long_description = fh.read()
 
diff --git a/tox.ini b/tox.ini
index 8bf19c8..5fa6fc1 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,7 +14,7 @@ deps =
     freezegun
     pyasn1
     pyasn1-modules
-    pymox
+    pymox < 1.2
     pytest-cov
     requests-mock
     rsa