diff --git a/core/modules/image/image.install b/core/modules/image/image.install
index f272603..af98651 100644
--- a/core/modules/image/image.install
+++ b/core/modules/image/image.install
@@ -200,6 +200,10 @@ function image_update_8003() {
     $field_config = config($config_name);
     if ($field_config->get('type') == 'image') {
       $settings = $field_config->get('settings');
+
+      // Some update hooks (like user_update_8011()) create image fields with
+      // the 'default_image' setting directly in the correct format. We do not
+      // need to update those.
       if (!is_array($settings['default_image'])) {
         if (!empty($settings['default_image'])) {
           $settings['default_image'] = array($settings['default_image']);
@@ -210,6 +214,7 @@ function image_update_8003() {
         $field_config->set('settings', $settings);
         $field_config->save();
       }
+
     }
   }