diff --git a/src/wuttafarm/web/views/users.py b/src/wuttafarm/web/views/users.py
index f35aef7..21e26d9 100644
--- a/src/wuttafarm/web/views/users.py
+++ b/src/wuttafarm/web/views/users.py
@@ -23,6 +23,8 @@
 Views for Users
 """
 
+import colander
+
 from wuttaweb.views import users as base
 
 
@@ -53,12 +55,12 @@ class UserView(base.UserView):
         # farmos_uuid
         if not self.creating:
             f.fields.append("farmos_uuid")
-            f.set_default("farmos_uuid", user.farmos_uuid)
+            f.set_default("farmos_uuid", user.farmos_uuid or colander.null)
 
         # drupal_id
         if not self.creating:
             f.fields.append("drupal_id")
-            f.set_default("drupal_id", user.drupal_id)
+            f.set_default("drupal_id", user.drupal_id or colander.null)
 
     def get_xref_buttons(self, user):
         buttons = []