diff --git a/src/wuttafarm/web/views/users.py b/src/wuttafarm/web/views/users.py
index 21e26d9..ffda747 100644
--- a/src/wuttafarm/web/views/users.py
+++ b/src/wuttafarm/web/views/users.py
@@ -55,11 +55,13 @@ class UserView(base.UserView):
         # farmos_uuid
         if not self.creating:
             f.fields.append("farmos_uuid")
+            f.set_readonly("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_readonly("drupal_id")
             f.set_default("drupal_id", user.drupal_id or colander.null)
 
     def get_xref_buttons(self, user):