diff --git a/scripts/lib/CIME/XML/namelist_definition.py b/scripts/lib/CIME/XML/namelist_definition.py
index dcb59bd2c85..ac0c7cdc7e0 100644
--- a/scripts/lib/CIME/XML/namelist_definition.py
+++ b/scripts/lib/CIME/XML/namelist_definition.py
@@ -321,11 +321,11 @@ def _user_modifiable_in_variable_definition(self, name):
         user_modifiable_only_by_xml = node.get('modify_via_xml')
         if user_modifiable_only_by_xml is not None:
             expect(False,
-                   "Cannot change %s in user_nl_xxx file, %s" %(name, user_modifiable_only_by_xml))
+                   "Cannot change %s in user_nl file: set via xml variable %s" %(name, user_modifiable_only_by_xml))
         user_cannot_modify = node.get('cannot_modify_by_user_nl')
         if user_cannot_modify is not None:
             expect(False,
-                   "Cannot change %s in user_nl_xxx file, %s" %(name, user_cannot_modify))
+                   "Cannot change %s in user_nl file: %s" %(name, user_cannot_modify))
 
     def validate(self, namelist,filename=None):
         """Validate a namelist object against this definition.