diff --git a/zaza/charm_tests/ceph/rbd_mirror/tests.py b/zaza/charm_tests/ceph/rbd_mirror/tests.py
index b108a62..65000ae 100644
--- a/zaza/charm_tests/ceph/rbd_mirror/tests.py
+++ b/zaza/charm_tests/ceph/rbd_mirror/tests.py
@@ -311,7 +311,7 @@ class CephRBDMirrorControlledFailoverTest(CephRBDMirrorBase):
             'up+replaying',
             application_name=self.application_name + self.site_b_app_suffix,
             model_name=self.site_b_model,
-            require_images_in['cinder-ceph', 'glance'])
+            require_images_in=['cinder-ceph', 'glance'])
 
 
 class CephRBDMirrorDisasterFailoverTest(CephRBDMirrorBase):