diff --git a/core/lib/Drupal/Core/Form/ConfigFormBase.php b/core/lib/Drupal/Core/Form/ConfigFormBase.php
index 77f8af970f..ce69474557 100644
--- a/core/lib/Drupal/Core/Form/ConfigFormBase.php
+++ b/core/lib/Drupal/Core/Form/ConfigFormBase.php
@@ -44,8 +44,8 @@ public function buildForm(array $form, FormStateInterface $form_state) {
     // By default, render the form using system-config-form.html.twig.
     $form['#theme'] = 'system_config_form';
 
-    // Add a post build callback so any form elements that #config_data_source
-    // blah @todo
+    // Add a post build callback so any properties that #config_data_source
+    // overrides can be marked as overridden.
     $form['#after_build'][] = '::checkConfigOverrides';
 
     return $form;
diff --git a/core/lib/Drupal/Core/Form/ConfigFormBaseTrait.php b/core/lib/Drupal/Core/Form/ConfigFormBaseTrait.php
index 7a6b89dc8d..fcf8ba6681 100644
--- a/core/lib/Drupal/Core/Form/ConfigFormBaseTrait.php
+++ b/core/lib/Drupal/Core/Form/ConfigFormBaseTrait.php
@@ -85,7 +85,7 @@ public function checkConfigOverrides(array $element, FormStateInterface $form_st
           '#theme' => 'config_overrides',
           '#overrides' => $overrides,
         ];
-        drupal_set_message(\Drupal::service('renderer')->render($override_output));
+        drupal_set_message(\Drupal::service('renderer')->render($override_output), 'warning');
       }
     }
     return $element;
@@ -118,8 +118,8 @@ protected function getConfigOverrides(array $element, array $overrides = []) {
       if ($value !== $original_value) {
         // There is an override.
         $overrides[$name][$key] = [
-          'original' => $original_value,
-          'override' => $value
+          'original' => var_export($original_value, TRUE),
+          'override' => var_export($value, TRUE),
           // It'd be nice to link back to the form element - probably need the
           // element key and parents.
           // 'form_element' =>