diff --git a/question/format/aiken/format.php b/question/format/aiken/format.php
index ab76310b157..951923368bc 100644
--- a/question/format/aiken/format.php
+++ b/question/format/aiken/format.php
@@ -61,6 +61,10 @@ class qformat_aiken extends qformat_default {
         return true;
     }
 
+    public function validate_file(stored_file $file): string {
+        return $this->validate_is_utf8_file($file);
+    }
+
     public function readquestions($lines) {
         $questions = array();
         $question = null;