diff --git a/contracts/ontology/requirements.txt b/contracts/ontology/requirements.txt
index 64be074..1589a45 100644
--- a/contracts/ontology/requirements.txt
+++ b/contracts/ontology/requirements.txt
@@ -60,7 +60,7 @@ python-dateutil==2.6.1
 python-debian==0.1.32
 pytz==2018.3
 pyxdg==0.25
-PyYAML==3.12
+PyYAML==5.4
 reportlab==3.4.0
 requests==2.22.0
 requests-unixsocket==0.1.5