diff --git a/tempest/api/image/v1/test_images.py b/tempest/api/image/v1/test_images.py
index b341ab7..76723f4 100644
--- a/tempest/api/image/v1/test_images.py
+++ b/tempest/api/image/v1/test_images.py
@@ -43,7 +43,8 @@
         else:
             msg = ("The container format and the disk format don't match. "
                    "Container format: %(container)s, Disk format: %(disk)s." %
-                   {'container': container_format, 'disk': disk_format})
+                   {'container': container_format, 'disk':
+                       CONF.image.disk_formats})
             raise exceptions.InvalidConfiguration(msg)
     else:
         disk_format = CONF.image.disk_formats[0]