diff --git a/bootstrap_forms.theme b/bootstrap_forms.theme
index 671c007..f258ca6 100644
--- a/bootstrap_forms.theme
+++ b/bootstrap_forms.theme
@@ -222,7 +222,7 @@ function bootstrap_forms_preprocess_form_element_label(&$variables) {
 
   if (isset($element['#tooltip_expand'])) {
     $tip = ['#theme' => 'tooltip'];
-    $variables['title']['#markup'] .= drupal_render($tip);
+    $variables['title']['#markup'] .= \Drupal::service('renderer')->render($tip);
 
   }