diff --git a/tests/conftest.py b/tests/conftest.py
index c738009..22a5b6c 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -88,6 +88,7 @@ account.store()
 import datetime
 import random
 from quixote import get_publisher
+from django.utils.timezone import make_aware
 
 from wcs.categories import Category
 from wcs.formdef import FormDef
@@ -140,7 +141,7 @@ agent.store()
 for i in range(50):
     formdata = formdef.data_class()()
     formdata.just_created()
-    formdata.receipt_time = datetime.datetime(2018, random.randrange(1, 13), random.randrange(1, 29)).timetuple()
+    formdata.receipt_time = make_aware(datetime.datetime(2018, random.randrange(1, 13), random.randrange(1, 29)))
     formdata.data = {'1': 'FOO BAR é %d' % i}
     if i%4 == 0:
         formdata.data['2'] = 'foo'
diff --git a/tests/test_wcs.py b/tests/test_wcs.py
index 18cbcf2..84ef7d8 100644
--- a/tests/test_wcs.py
+++ b/tests/test_wcs.py
@@ -24,6 +24,7 @@ import httmock
 import pytest
 import requests
 import utils
+from django.utils.timezone import make_aware
 from psycopg2.extensions import ISOLATION_LEVEL_AUTOCOMMIT
 
 
@@ -251,6 +252,7 @@ def test_dimension_stability(wcs, wcs_dir, postgres_db, tmpdir, olap_cmd, caplog
     script = """
 import datetime
 import random
+from django.utils.timezone import make_aware
 from quixote import get_publisher
 from wcs.formdef import FormDef
 formdef = FormDef.get_by_urlname('demande')
@@ -267,7 +269,7 @@ user = get_publisher().user_class.select()[0]
 
 formdata = formdef.data_class()()
 formdata.just_created()
-formdata.receipt_time = datetime.datetime(2018, random.randrange(1, 13), random.randrange(1, 29)).timetuple()
+formdata.receipt_time = make_aware(datetime.datetime(2018, random.randrange(1, 13), random.randrange(1, 29)))
 formdata.data = {'1': 'FOO BAR 1'}
 formdata.data['2'] = 'bazouka'
 formdata.data['2_display'] = 'bazouka'
diff --git a/wcs_olap/wcs_api.py b/wcs_olap/wcs_api.py
index 30c7a26..01aa698 100644
--- a/wcs_olap/wcs_api.py
+++ b/wcs_olap/wcs_api.py
@@ -101,7 +101,7 @@ class Evolution(BaseObject):
 
     def __init__(self, wcs_api, **kwargs):
         super().__init__(wcs_api, **kwargs)
-        self.time = isodate.parse_datetime(self.time)
+        self.time = isodate.parse_datetime(self.time[:19])  # skip microseconds and timezone
         self.parts = [BaseObject(wcs_api, **part) for part in self.parts or []]
         self.who = EvolutionUser(wcs_api, **self.who) if self.who else None