diff --git a/requirements_dev.txt b/requirements_dev.txt
index b8d5de0..4afd589 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -7,7 +7,7 @@ certifi==2018.10.15
 cffi==1.11.5
 chardet==3.0.4
 coverage==4.5.1
-cryptography==2.3.1
+cryptography==2.4.1
 docutils==0.14
 flake8==3.6.0
 idna==2.7