diff --git a/keystone/resource/core.py b/keystone/resource/core.py
index 0e9c209c12..9378a07b4d 100644
--- a/keystone/resource/core.py
+++ b/keystone/resource/core.py
@@ -119,19 +119,18 @@ class Manager(manager.Manager):
         if parent_ref['is_domain']:
             if parent_ref['id'] != domain['id']:
                 raise exception.ValidationError(
-                    message=_('Cannot create project, since its parent '
-                              '(%(domain_id)s) is acting as a domain, '
-                              'but project\'s specified parent_id '
-                              '(%(parent_id)s) does not match '
-                              'this domain_id.')
-                    % {'domain_id': domain['id'],
-                       'parent_id': parent_ref['id']})
+                    message=_('Cannot create project, the parent '
+                              '(%(parent_id)s) is acting as a domain, '
+                              'but this project\'s domain id (%(domain_id)s) '
+                              'does not match the parent\'s id.')
+                    % {'parent_id': parent_ref['id'],
+                       'domain_id': domain['id']})
         else:
             parent_domain_id = parent_ref.get('domain_id')
             if parent_domain_id != domain['id']:
                 raise exception.ValidationError(
                     message=_('Cannot create project, since it specifies '
-                              'its owner as domain %(domain_id)s, but '
+                              'its domain_id %(domain_id)s, but '
                               'specifies a parent in a different domain '
                               '(%(parent_domain_id)s).')
                     % {'domain_id': domain['id'],