django 1.8 doesn't allows both auto_now* and default on DateTimeField
diff --git a/xos/core/models/plcorebase.py b/xos/core/models/plcorebase.py
index 060570d..76c2e54 100644
--- a/xos/core/models/plcorebase.py
+++ b/xos/core/models/plcorebase.py
@@ -198,8 +198,8 @@
 
     # default values for created and updated are only there to keep evolution
     # from failing.
-    created = models.DateTimeField(auto_now_add=True, default=timezone.now)
-    updated = models.DateTimeField(default=timezone.now)
+    created = models.DateTimeField(auto_now_add=True)
+    updated = models.DateTimeField(auto_now=True)
     enacted = models.DateTimeField(null=True, blank=True, default=None)
     policed = models.DateTimeField(null=True, blank=True, default=None)