diff --git a/apps/files_trashbin/tests/trashbin.php b/apps/files_trashbin/tests/trashbin.php
index 1b5e955d2b..c53ed8d8a9 100644
--- a/apps/files_trashbin/tests/trashbin.php
+++ b/apps/files_trashbin/tests/trashbin.php
@@ -71,9 +71,10 @@ class Test_Trashbin extends \Test\TestCase {
 		//disable encryption
 		\OC_App::disable('encryption');
 
+		$config = \OC::$server->getConfig();
 		//configure trashbin
-		self::$rememberRetentionObligation = \OC_Config::getValue('trashbin_retention_obligation', Files_Trashbin\Expiration::DEFAULT_RETENTION_OBLIGATION);
-		\OC_Config::setValue('trashbin_retention_obligation', 'auto, 2');
+		self::$rememberRetentionObligation = $config->getSystemValue('trashbin_retention_obligation', Files_Trashbin\Expiration::DEFAULT_RETENTION_OBLIGATION);
+		$config->setSystemValue('trashbin_retention_obligation', 'auto, 2');
 
 		// register hooks
 		Files_Trashbin\Trashbin::registerHooks();
@@ -89,7 +90,7 @@ class Test_Trashbin extends \Test\TestCase {
 		// cleanup test user
 		\OC_User::deleteUser(self::TEST_TRASHBIN_USER1);
 
-		\OC_Config::setValue('trashbin_retention_obligation', self::$rememberRetentionObligation);
+		\OC::$server->getConfig()->setSystemValue('trashbin_retention_obligation', self::$rememberRetentionObligation);
 
 		\OC_Hook::clear();
 
diff --git a/lib/private/installer.php b/lib/private/installer.php
index 021e496392..fa9fc6704d 100644
--- a/lib/private/installer.php
+++ b/lib/private/installer.php
@@ -538,17 +538,20 @@ class OC_Installer{
 		if (is_null($info)) {
 			return false;
 		}
-		\OC::$server->getAppConfig()->setValue($app, 'installed_version', OC_App::getAppVersion($app));
+
+		$config = \OC::$server->getConfig();
+
+		$config->setAppValue($app, 'installed_version', OC_App::getAppVersion($app));
 		if (array_key_exists('ocsid', $info)) {
-			\OC::$server->getAppConfig()->setValue($app, 'ocsid', $info['ocsid']);
+			$config->setAppValue($app, 'ocsid', $info['ocsid']);
 		}
 
 		//set remote/public handlers
 		foreach($info['remote'] as $name=>$path) {
-			OCP\CONFIG::setAppValue('core', 'remote_'.$name, $app.'/'.$path);
+			$config->setAppValue('core', 'remote_'.$name, $app.'/'.$path);
 		}
 		foreach($info['public'] as $name=>$path) {
-			OCP\CONFIG::setAppValue('core', 'public_'.$name, $app.'/'.$path);
+			$config->setAppValue('core', 'public_'.$name, $app.'/'.$path);
 		}
 
 		OC_App::setAppTypes($info['id']);
@@ -563,7 +566,7 @@ class OC_Installer{
 	 */
 	public static function checkCode($folder) {
 		// is the code checker enabled?
-		if(!OC_Config::getValue('appcodechecker', false)) {
+		if(!\OC::$server->getConfig()->getSystemValue('appcodechecker', false)) {
 			return true;
 		}
 
diff --git a/lib/private/setup.php b/lib/private/setup.php
index 2c959622cc..814d78679e 100644
--- a/lib/private/setup.php
+++ b/lib/private/setup.php
@@ -463,7 +463,9 @@ class Setup {
 		$content.= "</ifModule>\n\n";
 		$content.= "# section for Apache 2.2 and 2.4\n";
 		$content.= "IndexIgnore *\n";
-		file_put_contents(\OC_Config::getValue('datadirectory', \OC::$SERVERROOT.'/data').'/.htaccess', $content);
-		file_put_contents(\OC_Config::getValue('datadirectory', \OC::$SERVERROOT.'/data').'/index.html', '');
+
+		$baseDir = \OC::$server->getConfig()->getSystemValue('datadirectory', \OC::$SERVERROOT . '/data');
+		file_put_contents($baseDir . '/.htaccess', $content);
+		file_put_contents($baseDir . '/index.html', '');
 	}
 }