diff --git a/lower-constraints.txt b/lower-constraints.txt
index adde6d7..d2f2ddb 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -44,7 +44,7 @@ python-blazarclient==1.0.1
 python-dateutil==2.7.0
 python-mimeparse==1.6.0
 pytz==2018.3
-PyYAML==3.12
+PyYAML==3.13
 rcssmin==1.0.6
 requests==2.18.4
 rfc3986==1.1.0