diff --git a/apps/files/appinfo/update.php b/apps/files/appinfo/update.php
index 5f054f266b..de635e5ce6 100644
--- a/apps/files/appinfo/update.php
+++ b/apps/files/appinfo/update.php
@@ -2,7 +2,7 @@
 
 // this drops the keys below, because they aren't needed anymore
 // core related
-if (version_compare(\OC_Config::getValue('version', '0.0.0'), '7.0.0', '<')) {
-	\OC_Config::deleteKey('allowZipDownload');
-	\OC_Config::deleteKey('maxZipInputSize');
+if (version_compare(\OCP\Config::getSystemValue('version', '0.0.0'), '7.0.0', '<')) {
+	\OCP\Config::deleteSystemValue('allowZipDownload');
+	\OCP\Config::deleteSystemValue('maxZipInputSize');
 }
diff --git a/lib/public/config.php b/lib/public/config.php
index 8e3791b449..ea3e0c1372 100644
--- a/lib/public/config.php
+++ b/lib/public/config.php
@@ -70,6 +70,16 @@ class Config {
 		return true;
 	}
 
+	/**
+	 * Deletes a value from config.php
+	 * @param string $key key
+	 *
+	 * This function deletes the value from config.php.
+	 */
+	public static function deleteSystemValue( $key ) {
+		return \OC_Config::deleteKey( $key );
+	}
+
 	/**
 	 * Gets the config value
 	 * @param string $app app