diff --git a/doc/requirements.txt b/doc/requirements.txt
index 86372e0..8802c39 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -14,7 +14,7 @@ pathtools==0.1.2
 port-for==0.3.1
 Pygments==2.1.3
 pytz==2016.1
-PyYAML==3.11
+PyYAML==5.4
 recommonmark==0.4.0
 singledispatch==3.4.0.3
 six==1.10.0