diff --git a/doc/requirements.txt b/doc/requirements.txt
index 0c9c95a..2d8fb45 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -12,7 +12,7 @@ MarkupSafe==0.23
 pathtools==0.1.2
 Pygments==2.1.1
 pytz==2015.7
-PyYAML==3.11
+PyYAML==5.4
 recommonmark==0.4.0
 singledispatch==3.4.0.3
 six==1.10.0