diff --git a/tox.ini b/tox.ini
index 0e416f6..8e2d4b1 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,7 +14,7 @@ setenv = VIRTUAL_ENV={envdir}
          NOSE_OPENSTACK_SHOW_ELAPSED=1
          DJANGO_SETTINGS_MODULE=zaqar_ui.test.settings
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
+  -c{env:TOX_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/test-requirements.txt
 commands =
@@ -79,7 +79,7 @@ commands =
 
 [testenv:docs]
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
+  -c{env:TOX_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
   # zaqar-ui doc generated the module reference,
   # so requirements.txt should be here to apply upper-constraints
   -r{toxinidir}/requirements.txt
diff --git a/zaqar_ui/api/rest/zaqar.py b/zaqar_ui/api/rest/zaqar.py
index 55b3983..4788d9c 100644
--- a/zaqar_ui/api/rest/zaqar.py
+++ b/zaqar_ui/api/rest/zaqar.py
@@ -15,6 +15,7 @@
 import json
 import yaml
 
+from django.utils.translation import ugettext_lazy as _
 from django.views import generic
 from openstack_dashboard.api.rest import urls
 from openstack_dashboard.api.rest import utils as rest_utils