diff --git a/netconf/constants.py b/netconf/constants.py
index 976ddff..8e6bf92 100644
--- a/netconf/constants.py
+++ b/netconf/constants.py
@@ -28,6 +28,9 @@
     CERTS_DIRECTORY = 'security/certificates'
     CLIENT_CRED_DIRECTORY = 'security/client_credentials'
 
+    # YANG message definition file - generated file
+    YANG_MESSAGE_DEFINITIONS_FILE='yang_message_defs.py'
+
     # Datastores
     RUNNING = "running"
     CANDIDATE = "candidate"