diff --git a/requirements_dev.txt b/requirements_dev.txt
index 928e7a6..73f2174 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -6,7 +6,7 @@ flake8==3.5.0
 tox==3.1.2
 coverage==4.5.1
 Sphinx==1.8.0
-cryptography==2.3
+cryptography==2.3.1
 PyYAML==3.12
 pytest==3.8.0
 pytest-runner==4.2