diff --git a/requirements_dev.txt b/requirements_dev.txt
index 582e704..3a17b55 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -7,7 +7,7 @@ tox==3.14.5
 coverage==5.0.4
 Sphinx==2.3.1
 cryptography==2.8
-PyYAML==5.3
+PyYAML==5.3.1
 pytest==5.3.5
 pytest-runner==5.2
 vcrpy==2.1.1