diff -u b/rdf_builder/src/Form/ContentBuilderForm.php b/rdf_builder/src/Form/ContentBuilderForm.php
--- b/rdf_builder/src/Form/ContentBuilderForm.php
+++ b/rdf_builder/src/Form/ContentBuilderForm.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\rdf_builder\Form;
 
+use Drupal\Component\Utility\Html;
 use Drupal\Component\Utility\String;
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
@@ -197,14 +198,14 @@
       '#regions' => array(),
       '#attributes' => array(
         'class' => array('rdfui-field-mappings'),
-        'id' => drupal_html_id('rdf-builder'),
+        'id' => Html::getId('rdf-builder'),
       ),
     );
 
     foreach ($properties as $key => $value) {
       $table[$key] = array(
         '#attributes' => array(
-          'id' => drupal_html_class($key),
+          'id' => Html::getClass($key),
         ),
         'enable' => array(
           '#type' => 'checkbox',