diff --git a/horizon/middleware.py b/horizon/middleware.py
index 91906e8c71..5c510045d5 100644
--- a/horizon/middleware.py
+++ b/horizon/middleware.py
@@ -21,9 +21,9 @@
 Middleware provided and used by Horizon.
 """
 
-import datetime
 import json
 import logging
+import time
 
 from django.conf import settings  # noqa
 from django.contrib.auth import REDIRECT_FIELD_NAME  # noqa
@@ -61,7 +61,7 @@ class HorizonMiddleware(object):
             timeout = 1800
 
         last_activity = request.session.get('last_activity', None)
-        timestamp = datetime.datetime.now()
+        timestamp = int(time.time())
         request.horizon = {'dashboard': None,
                            'panel': None,
                            'async_messages': []}
@@ -98,7 +98,8 @@ class HorizonMiddleware(object):
                         }
                     )
 
-        if last_activity and (timestamp - last_activity).seconds > timeout:
+        if (isinstance(last_activity, int)
+                and (timestamp - last_activity) > timeout):
             request.session.pop('last_activity')
             response = HttpResponseRedirect(
                 '%s?next=%s' % (settings.LOGOUT_URL, request.path))
diff --git a/horizon/test/tests/middleware.py b/horizon/test/tests/middleware.py
index 3c539b12ef..2a2ad41a07 100644
--- a/horizon/test/tests/middleware.py
+++ b/horizon/test/tests/middleware.py
@@ -15,7 +15,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import datetime
+import time
 
 from django.conf import settings  # noqa
 
@@ -46,8 +46,7 @@ class MiddlewareTests(test.TestCase):
             timeout = settings.SESSION_TIMEOUT
         except AttributeError:
             timeout = 1800
-        request.session['last_activity'] =\
-            datetime.datetime.now() - datetime.timedelta(seconds=timeout + 10)
+        request.session['last_activity'] = int(time.time()) - (timeout + 10)
         mw = middleware.HorizonMiddleware()
         resp = mw.process_request(request)
         self.assertEqual(resp.status_code, 302)
diff --git a/openstack_dashboard/settings.py b/openstack_dashboard/settings.py
index ad36e1afb8..9871152b32 100644
--- a/openstack_dashboard/settings.py
+++ b/openstack_dashboard/settings.py
@@ -171,10 +171,15 @@ SESSION_COOKIE_HTTPONLY = True
 SESSION_EXPIRE_AT_BROWSER_CLOSE = True
 SESSION_COOKIE_SECURE = False
 SESSION_TIMEOUT = 1800
+
 # When using cookie-based sessions, log error when the session cookie exceeds
 # the following size (common browsers drop cookies above a certain size):
 SESSION_COOKIE_MAX_SIZE = 4093
 
+# when doing upgrades, it may be wise to stick to PickleSerializer
+# TODO(mrunge): remove after Icehouse
+SESSION_SERIALIZER = 'django.contrib.sessions.serializers.PickleSerializer'
+
 gettext_noop = lambda s: s
 LANGUAGES = (
     ('en', gettext_noop('English')),