diff --git a/requirements_dev.txt b/requirements_dev.txt
index 5ab5b7b..073a46c 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -6,6 +6,6 @@ flake8==3.5.0
 tox==2.7.0
 coverage==4.4.1
 Sphinx==1.7.2
-cryptography==1.9
+cryptography==2.5
 PyYAML==3.12