diff --git a/ceilometer/alarm/evaluator/__init__.py b/ceilometer/alarm/evaluator/__init__.py
index 03329b1d5..f09f478f3 100644
--- a/ceilometer/alarm/evaluator/__init__.py
+++ b/ceilometer/alarm/evaluator/__init__.py
@@ -93,7 +93,7 @@ class Evaluator(object):
         if not alarm.time_constraints:
             return True
 
-        now_utc = timeutils.utcnow()
+        now_utc = timeutils.utcnow().replace(tzinfo=pytz.utc)
         for tc in alarm.time_constraints:
             tz = pytz.timezone(tc['timezone']) if tc['timezone'] else None
             now_tz = now_utc.astimezone(tz) if tz else now_utc
diff --git a/ceilometer/tests/alarm/evaluator/test_base.py b/ceilometer/tests/alarm/evaluator/test_base.py
index 3a0b62b67..1aa6f24a2 100644
--- a/ceilometer/tests/alarm/evaluator/test_base.py
+++ b/ceilometer/tests/alarm/evaluator/test_base.py
@@ -18,7 +18,6 @@
 """
 import datetime
 import mock
-import pytz
 
 from ceilometer.alarm import evaluator
 from ceilometer.openstack.common import test
@@ -122,6 +121,9 @@ class TestEvaluatorBaseClass(test.BaseTestCase):
     @mock.patch.object(timeutils, 'utcnow')
     def test_base_time_constraints_timezone(self, mock_utcnow):
         alarm = mock.MagicMock()
+        cls = evaluator.Evaluator
+        mock_utcnow.return_value = datetime.datetime(2014, 1, 1, 11, 0, 0)
+
         alarm.time_constraints = [
             {'name': 'test',
              'description': 'test',
@@ -129,13 +131,13 @@ class TestEvaluatorBaseClass(test.BaseTestCase):
              'duration': 10800,  # 3 hours
              'timezone': 'Europe/Ljubljana'}
         ]
-        cls = evaluator.Evaluator
-        dt_eu = datetime.datetime(2014, 1, 1, 12, 0, 0,
-                                  tzinfo=pytz.timezone('Europe/Ljubljana'))
-        dt_us = datetime.datetime(2014, 1, 1, 12, 0, 0,
-                                  tzinfo=pytz.timezone('US/Eastern'))
-        mock_utcnow.return_value = dt_eu.astimezone(pytz.UTC)
         self.assertTrue(cls.within_time_constraint(alarm))
 
-        mock_utcnow.return_value = dt_us.astimezone(pytz.UTC)
+        alarm.time_constraints = [
+            {'name': 'test2',
+             'description': 'test2',
+             'start': '0 11 * * *',  # daily at 11:00
+             'duration': 10800,  # 3 hours
+             'timezone': 'US/Eastern'}
+        ]
         self.assertFalse(cls.within_time_constraint(alarm))