diff --git a/requirements_dev.txt b/requirements_dev.txt
index b38b7ec..acd1248 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -9,5 +9,5 @@ tox==2.3.1
 coverage==4.1
 Sphinx==1.4.4
 cryptography==1.4
-PyYAML==3.11
+PyYAML==5.1