diff --git a/requirements_dev.txt b/requirements_dev.txt
index 7d7afd3..abfbabc 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -7,4 +7,4 @@ tox==2.9.1
 coverage==4.5.1
 Sphinx==1.6.5
 cryptography==2.1.4
-PyYAML==3.12
+PyYAML==6.0