diff --git a/servers/cromwell/requirements.txt b/servers/cromwell/requirements.txt
index 1aa30608b..d4537f6eb 100644
--- a/servers/cromwell/requirements.txt
+++ b/servers/cromwell/requirements.txt
@@ -18,7 +18,7 @@ MarkupSafe==1.0
 pathlib==1.0.1
 python-dateutil==2.6.0
 pytz==2018.5
-PyYAML==5.1
+PyYAML==5.4
 requests==2.20.0
 six==1.11.0
 swagger-spec-validator==2.3.1