diff --git a/docs/server/requirements.txt b/docs/server/requirements.txt
index 467bc009..5da3beed 100644
--- a/docs/server/requirements.txt
+++ b/docs/server/requirements.txt
@@ -3,6 +3,6 @@ recommonmark>=0.4.0
 sphinx-rtd-theme>=0.1.9
 sphinxcontrib-napoleon>=0.4.4
 sphinxcontrib-httpdomain>=1.5.0
-pyyaml~=3.12
+pyyaml>=4.2b1
 aafigure>=0.6
 packaging~=18.0