diff --git a/redfish/managers/test_certificate.robot b/redfish/managers/test_certificate.robot
index 71f8ac5..e7e70d1 100644
--- a/redfish/managers/test_certificate.robot
+++ b/redfish/managers/test_certificate.robot
@@ -18,7 +18,7 @@
 
 ${invalid_value}  abc
 ${ROOT_CA_FILE_PATH}  /etc/ssl/certs/authority/*
-${keybit_length}  2048
+${keybit_length}  ${2048}
 
 ** Test Cases **