diff --git a/requirements_dev.txt b/requirements_dev.txt
index d6eb02f..c6aabeb 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -7,7 +7,7 @@ tox==2.3.1
 coverage==4.1
 Sphinx==1.4.8
 cryptography==1.7
-PyYAML==5.1
+PyYAML==5.4
 pytest==2.9.2
 pytest-runner==2.11.1
 lenstronomy>=0.0.6