diff --git a/requirements_dev.txt b/requirements_dev.txt
index 5c9dcb6..deb3423 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -7,5 +7,5 @@ tox==2.3.1
 coverage==4.1
 Sphinx==1.4.8
 cryptography==1.7
-PyYAML==3.11
+PyYAML==5.1