diff --git a/heat_tempest_plugin/common/test.py b/heat_tempest_plugin/common/test.py
index d719ad0..97d8d8c 100644
--- a/heat_tempest_plugin/common/test.py
+++ b/heat_tempest_plugin/common/test.py
@@ -60,6 +60,12 @@
     return False
 
 
+def isotime(at):
+    if at is None:
+        return None
+    return at.strftime('%Y-%m-%dT%H:%M:%SZ')
+
+
 def rand_name(name=''):
     randbits = six.text_type(random.randint(1, 0x7fffffff))
     if name:
diff --git a/heat_tempest_plugin/tests/scenario/test_aodh_alarm.py b/heat_tempest_plugin/tests/scenario/test_aodh_alarm.py
index 97e5c8d..3108c1e 100644
--- a/heat_tempest_plugin/tests/scenario/test_aodh_alarm.py
+++ b/heat_tempest_plugin/tests/scenario/test_aodh_alarm.py
@@ -11,7 +11,6 @@
 #    under the License.
 
 import datetime
-from heat.common import timeutils
 from oslo_log import log as logging
 
 from heat_tempest_plugin.common import test
@@ -48,8 +47,9 @@
         parameters = {'metric_id': metric['id']}
         stack_identifier = self.stack_create(template=self.template,
                                              parameters=parameters)
-        measures = [{'timestamp': timeutils.isotime(datetime.datetime.now()),
-                     'value': 100}, {'timestamp': timeutils.isotime(
+
+        measures = [{'timestamp': test.isotime(datetime.datetime.now()),
+                     'value': 100}, {'timestamp': test.isotime(
                          datetime.datetime.now() + datetime.timedelta(
                              minutes=1)), 'value': 100}]
         # send measures(should cause the alarm to fire)