diff --git a/core/themes/seven/seven.theme b/core/themes/seven/seven.theme
index 6aa8baa27f4..fb522e8ae9f 100644
--- a/core/themes/seven/seven.theme
+++ b/core/themes/seven/seven.theme
@@ -201,16 +201,16 @@ function seven_form_node_form_alter(&$form, FormStateInterface $form_state) {
 /**
  * Implements hook_library_info_alter().
  */
-function seven_library_info_alter(&$libraries) {
-  if (isset($libraries['drupal.vertical-tabs'])) {
+function seven_library_info_alter(&$libraries, $extension) {
+  if ($extension == 'core' && isset($libraries['drupal.vertical-tabs'])) {
     unset($libraries['drupal.vertical-tabs']['css']['component']['misc/vertical-tabs.css']);
     $libraries['drupal.vertical-tabs']['dependencies'][] = 'seven/vertical-tabs';
   }
-  if (isset($libraries['jquery.ui'])) {
+  if ($extension == 'core' && isset($libraries['jquery.ui'])) {
     unset($libraries['jquery.ui']['css']['theme']['assets/vendor/jquery.ui/themes/base/theme.css']);
     $libraries['jquery.ui']['dependencies'][] = 'seven/seven.jquery.ui';
   }
-  if (isset($libraries['drupal.dialog'])) {
+  if ($extension == 'core' && isset($libraries['drupal.dialog'])) {
     unset($libraries['drupal.dialog']['css']['theme']['misc/dialog.theme.css']);
     $libraries['drupal.dialog']['dependencies'][] = 'seven/seven.drupal.dialog';
   }