diff --git a/src/Plugin/WebformScore/Contains.php b/src/Plugin/WebformScore/Contains.php
index 0bd6114..dcfc655 100644
--- a/src/Plugin/WebformScore/Contains.php
+++ b/src/Plugin/WebformScore/Contains.php
@@ -2,7 +2,6 @@
 
 namespace Drupal\webform_score\Plugin\WebformScore;
 
-use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\TypedData\TypedDataInterface;
 use Drupal\webform_score\Plugin\WebformScoreInterface;
@@ -35,11 +34,11 @@ class Contains extends WebformScoreBase implements WebformScoreInterface {
     $answer = $answer->getValue();
     $expected = $this->configuration['expected'];
     if (!$this->configuration['case_sensitive']) {
-      $answer = Unicode::strtolower($answer);
-      $expected = Unicode::strtolower($expected);
+      $answer = mb_strtolower($answer);
+      $expected = mb_strtolower($expected);
     }
 
-    return Unicode::strpos($answer, $expected) === FALSE ? 0 : $this->getMaxScore();
+    return mb_strpos($answer, $expected) === FALSE ? 0 : $this->getMaxScore();
   }
 
   /**