diff --git a/zaza/openstack/charm_tests/kerberos/setup.py b/zaza/openstack/charm_tests/kerberos/setup.py
index f58a961..fadd7a9 100644
--- a/zaza/openstack/charm_tests/kerberos/setup.py
+++ b/zaza/openstack/charm_tests/kerberos/setup.py
@@ -113,6 +113,8 @@ def retrieve_and_attach_keytab():
                                    'keystone_keytab',
                                    tmp_file)
 
+    zaza.model.block_until_all_units_idle()
+
 
 def openstack_setup_kerberos():
     """Create a test domain, project, and user for kerberos tests."""