diff --git a/requirements.in b/requirements.in
index 8098683..a961d05 100644
--- a/requirements.in
+++ b/requirements.in
@@ -14,6 +14,6 @@
 CherryPy>=18.1.2
 jsonschema>=3.2.0
 python-keystoneclient
-pyyaml
+pyyaml==5.4.1
 requests
 tacacs_plus