diff --git a/core/Command/Db/ConvertMysqlToMB4.php b/core/Command/Db/ConvertMysqlToMB4.php
index 286274753e..38aff8b09d 100644
--- a/core/Command/Db/ConvertMysqlToMB4.php
+++ b/core/Command/Db/ConvertMysqlToMB4.php
@@ -22,6 +22,7 @@
 namespace OC\Core\Command\Db;
 
 use Doctrine\DBAL\Platforms\MySqlPlatform;
+use OC\DB\MySqlTools;
 use OC\Migration\ConsoleOutput;
 use OC\Repair\Collation;
 use OCP\IConfig;
@@ -71,18 +72,17 @@ class ConvertMysqlToMB4 extends Command {
 			return 1;
 		}
 
-		$oldValue = $this->config->getSystemValue('mysql.utf8mb4', false);
-		// enable charset
-		$this->config->setSystemValue('mysql.utf8mb4', true);
-
-		if (!$this->connection->supports4ByteText()) {
+		$tools = new MySqlTools();
+		if (!$tools->supports4ByteCharset($this->connection)) {
 			$url = $this->urlGenerator->linkToDocs('admin-mysql-utf8mb4');
 			$output->writeln("The database is not properly setup to use the charset utf8mb4.");
 			$output->writeln("For more information please read the documentation at $url");
-			$this->config->setSystemValue('mysql.utf8mb4', $oldValue);
 			return 1;
 		}
 
+		// enable charset
+		$this->config->setSystemValue('mysql.utf8mb4', true);
+
 		// run conversion
 		$coll = new Collation($this->config, $this->logger, $this->connection, false);
 		$coll->run(new ConsoleOutput($output));
diff --git a/lib/private/DB/MySqlTools.php b/lib/private/DB/MySqlTools.php
new file mode 100644
index 0000000000..32f1de887c
--- /dev/null
+++ b/lib/private/DB/MySqlTools.php
@@ -0,0 +1,49 @@
+<?php
+/**
+ * @author Thomas Müller <thomas.mueller@tmit.eu>
+ *
+ * @copyright Copyright (c) 2017, ownCloud GmbH
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OC\DB;
+
+use OCP\IDBConnection;
+
+/**
+* Various MySQL specific helper functions.
+*/
+class MySqlTools {
+
+	/**
+	 * @param Connection $connection
+	 * @return bool
+	 */
+	public function supports4ByteCharset(IDBConnection $connection) {
+		foreach (['innodb_file_format' => 'Barracuda', 'innodb_large_prefix' => 'ON', 'innodb_file_per_table' => 'ON'] as $var => $val) {
+			$result = $connection->executeQuery("SHOW VARIABLES LIKE '$var'");
+			$rows = $result->fetch();
+			$result->closeCursor();
+			if ($rows === false) {
+				return false;
+			}
+			if (strcasecmp($rows['Value'], $val) !== 0) {
+				return false;
+			}
+		}
+		return true;
+	}
+}
diff --git a/lib/private/Setup/MySQL.php b/lib/private/Setup/MySQL.php
index d72a106053..3f3ad6d958 100644
--- a/lib/private/Setup/MySQL.php
+++ b/lib/private/Setup/MySQL.php
@@ -27,7 +27,7 @@
  */
 namespace OC\Setup;
 
-use OC\DB\ConnectionFactory;
+use OC\DB\MySqlTools;
 use OCP\IDBConnection;
 
 class MySQL extends AbstractDatabase {
@@ -38,9 +38,12 @@ class MySQL extends AbstractDatabase {
 		$connection = $this->connect(['dbname' => null]);
 
 		// detect mb4
-		if (is_null($this->config->getSValue('mysql.utf8mb4', null)) && $this->supports4ByteCharset($connection)) {
-			$this->config->setValue('mysql.utf8mb4', true);
-			$connection = $this->connect();
+		if (is_null($this->config->getValue('mysql.utf8mb4', null))) {
+			$tools = new MySqlTools();
+			if ($tools->supports4ByteCharset($connection)) {
+				$this->config->setValue('mysql.utf8mb4', true);
+				$connection = $this->connect();
+			}
 		}
 
 		$this->createSpecificUser($username, $connection);
@@ -169,23 +172,4 @@ class MySQL extends AbstractDatabase {
 			'dbpassword' => $this->dbPassword,
 		]);
 	}
-
-	/**
-	 * @param IDBConnection $connection
-	 * @return bool
-	 */
-	private function supports4ByteCharset(IDBConnection $connection) {
-		foreach (['innodb_file_format' => 'Barracuda', 'innodb_large_prefix' => 'ON', 'innodb_file_per_table' => 'ON'] as $var => $val) {
-			$result = $connection->executeQuery("SHOW VARIABLES LIKE '$var'");
-			$rows = $result->fetch();
-			$result->closeCursor();
-			if ($rows === false) {
-				return false;
-			}
-			if (strcasecmp($rows['Value'], $val) === 0) {
-				return false;
-			}
-		}
-		return true;
-	}
 }