diff --git a/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
index d88633f..d05ea49 100644
--- a/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
@@ -266,16 +266,16 @@ protected function createKeysSql($spec) {
     $keys = array();
 
     if (!empty($spec['primary key'])) {
-      $keys[] = 'PRIMARY KEY (' . $this->createKeysSqlHelper($spec['primary key']) . ')';
+      $keys[] = 'PRIMARY KEY (' . $this->createKeysSql($spec['primary key']) . ')';
     }
     if (!empty($spec['unique keys'])) {
       foreach ($spec['unique keys'] as $key => $fields) {
-        $keys[] = 'UNIQUE KEY `' . $key . '` (' . $this->createKeysSqlHelper($fields) . ')';
+        $keys[] = 'UNIQUE KEY `' . $key . '` (' . $this->createKeysSql($fields) . ')';
       }
     }
     if (!empty($spec['indexes'])) {
       foreach ($spec['indexes'] as $index => $fields) {
-        $keys[] = 'INDEX `' . $index . '` (' . $this->createKeysSqlHelper($fields) . ')';
+        $keys[] = 'INDEX `' . $index . '` (' . $this->createKeysSql($fields) . ')';
       }
     }
 
@@ -295,19 +295,6 @@ protected function createKeySql($fields) {
     return implode(', ', $return);
   }
 
-  protected function createKeysSqlHelper($fields) {
-    $return = array();
-    foreach ($fields as $field) {
-      if (is_array($field)) {
-        $return[] = '`' . $field[0] . '`(' . $field[1] . ')';
-      }
-      else {
-        $return[] = '`' . $field . '`';
-      }
-    }
-    return implode(', ', $return);
-  }
-
   public function renameTable($table, $new_name) {
     if (!$this->tableExists($table)) {
       throw new SchemaObjectDoesNotExistException(t("Cannot rename @table to @table_new: table @table doesn't exist.", array('@table' => $table, '@table_new' => $new_name)));