diff -u b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
--- b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
@@ -12,6 +12,7 @@
 use Drupal\Core\Database\Query\Condition;
 use Drupal\Core\Database\SchemaObjectExistsException;
 use Drupal\Core\Database\SchemaObjectDoesNotExistException;
+use Drupal\Component\Utility\Unicode;
 use Drupal\Core\Database\Schema as DatabaseSchema;
 
 /**
@@ -492,7 +493,7 @@
     // Truncate comment to maximum comment length.
     if (isset($length)) {
       // Add table prefixes before truncating.
-      $comment = truncate_utf8($this->connection->prefixTables($comment), $length, TRUE, TRUE);
+      $comment = Unicode::truncate($this->connection->prefixTables($comment), $length, TRUE, TRUE);
     }
 
     return $this->connection->quote($comment);