diff --git a/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
index e033bd5..4c3c379 100644
--- a/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
@@ -492,7 +492,7 @@ public function prepareComment($comment, $length = NULL) {
     // Truncate comment to maximum comment length.
     if (isset($length)) {
       // Add table prefixes before truncating.
-      $comment = substr($this->connection->prefixTables($comment), 0, $length);
+      $comment = truncate_utf8($this->connection->prefixTables($comment), $length, TRUE, TRUE);
     }
 
     return $this->connection->quote($comment);