diff --git a/xos/core/models/attic/xosbase_header.py b/xos/core/models/attic/xosbase_header.py
index 13e628a..0923c04 100644
--- a/xos/core/models/attic/xosbase_header.py
+++ b/xos/core/models/attic/xosbase_header.py
@@ -16,6 +16,7 @@
 
 import datetime
 import time
+import calendar
 import json
 import pytz
 import inspect
@@ -48,7 +49,7 @@
         # json can't serialize DstTzInfo
         return str(obj)
     elif hasattr(obj, 'timetuple'):
-        return time.mktime(obj.timetuple())
+        return calendar.timegm(obj.timetuple())
     else:
         return obj
 
diff --git a/xos/core/models/user.py b/xos/core/models/user.py
index 83595f9..47c69e2 100644
--- a/xos/core/models/user.py
+++ b/xos/core/models/user.py
@@ -13,8 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
-import datetime
 import hashlib
 import os
 import sys