diff --git a/requirements.txt b/requirements.txt
index a54e132..4616754 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,5 +8,5 @@ contrail-api-client==2005
 future==0.18.2
 six==1.15.0
 requests==2.24.0
-pyyaml
+pyyaml<6.0.0
 os-testr