diff --git a/Chapter11/app/requirements.txt b/Chapter11/app/requirements.txt
index 5b5a84c..653d2ec 100644
--- a/Chapter11/app/requirements.txt
+++ b/Chapter11/app/requirements.txt
@@ -59,7 +59,7 @@ python-dateutil==2.7.5
 python-Levenshtein==0.12.0
 python-utils==2.3.0
 pytz==2018.7
-PyYAML==3.13
+PyYAML==5.4
 pyzmq==17.1.2
 QtAwesome==0.5.3
 qtconsole==4.4.3