diff --git a/lib/legacy/preferences.php b/lib/legacy/preferences.php
index 8bfac849a4a44f2a151a097ac42ac5b49917ee40..7b4cfca96bcfa10eaccb5e47dbc8c4a9a644ce17 100644
--- a/lib/legacy/preferences.php
+++ b/lib/legacy/preferences.php
@@ -100,7 +100,7 @@ class OC_Preferences{
 	 *
 	 * Deletes a key.
 	 */
-	public function deleteKey( $user, $app, $key ) {
+	public static function deleteKey( $user, $app, $key ) {
 		self::$object->deleteKey( $user, $app, $key );
 	}