diff --git a/src/Controller/SimpleReservationAdminController.php b/src/Controller/SimpleReservationAdminController.php
index a9c4513..7e82345 100644
--- a/src/Controller/SimpleReservationAdminController.php
+++ b/src/Controller/SimpleReservationAdminController.php
@@ -13,6 +13,7 @@ use Drupal\Core\Entity\Query\QueryFactory;
 use Drupal\node\Entity\NodeType;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Entity\EntityManagerInterface;
+use \Drupal\Component\Utility\String;
 
 /**
  * ADMINISTRATION
@@ -94,9 +95,9 @@ class SimpleReservationAdminController implements ContainerInjectionInterface {
     foreach ($items as $item) {
       $rows[] = array(
         'SimpleReservation',
-        check_plain($item->name),
-        check_plain($item->description),
-        check_plain($item->comment),
+        String::checkPlain($item->name),
+        String::checkPlain($item->description),
+        String::checkPlain($item->comment),
         ($item->status ? t('available') : t('not available')),
         l(t('Edit'), $path . 'edit/' . $item->iid),
         l(t('Delete'), $path . 'delete/' . $item->iid),
diff --git a/src/Form/SimpleReservationAdminNodeTypeForm.php b/src/Form/SimpleReservationAdminNodeTypeForm.php
index 8cb6cf1..b3ca793 100644
--- a/src/Form/SimpleReservationAdminNodeTypeForm.php
+++ b/src/Form/SimpleReservationAdminNodeTypeForm.php
@@ -14,6 +14,7 @@ use Symfony\Component\DependencyInjection\ContainerInterface;
 use Drupal\node\Entity\NodeType;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Component\Utility\String;
 
 /**
  * Configure file system settings for this site.
@@ -120,10 +121,10 @@ class SimpleReservationAdminNodeTypeForm extends ConfigFormBase {
       if(!@$node_type_field[$item->node_type][$item->nt_description]) $nt_description = $item->nt_description;
         else $nt_description = $node_type_field[$item->node_type][$item->nt_description];
       $rows[] = array(
-        check_plain($node_type),
-        check_plain($nt_name),
-        check_plain($nt_description),
-        check_plain($nt_comment),
+        String::checkPlain($node_type),
+        String::checkPlain($nt_name),
+        String::checkPlain($nt_description),
+        String::checkPlain($nt_comment),
         l($this->t('Edit'), $path . 'nodetype/edit/' . $item->iid),
         l($this->t('Remove'), $path . 'nodetype/delete/' . $item->iid),
       );