diff --git a/app/controllers/epp/domains_controller.rb b/app/controllers/epp/domains_controller.rb
index fa0003756..46012a738 100644
--- a/app/controllers/epp/domains_controller.rb
+++ b/app/controllers/epp/domains_controller.rb
@@ -103,13 +103,19 @@ module Epp
     def update
       authorize! :update, @domain, @password
 
-      updated = @domain.update(params[:parsed_frame], current_user)
+      updated = Domain.transaction(isolation: isolation_level) do
+        @domain.update(params[:parsed_frame], current_user)
+      end
       (handle_errors(@domain) && return) unless updated
 
       pending = @domain.epp_pending_update.present?
       render_epp_response "/epp/domains/success#{'_pending' if pending}"
     end
 
+    def isolation_level
+      :serializable unless Rails.env.test?
+    end
+
     def delete
       authorize! :delete, @domain, @password