diff --git a/doc/requirements.txt b/doc/requirements.txt
index 6da433c..9c1e6bc 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -15,7 +15,7 @@ pathtools==0.1.2
 port-for==0.3.1
 Pygments==2.2.0
 pytz==2017.3
-PyYAML==3.12
+PyYAML==5.4
 recommonmark==0.4.0
 requests==2.18.4
 six==1.11.0