diff --git a/src/Spout/Common/Singleton.php b/src/Spout/Common/Singleton.php
index 015ede8..9da6f79 100644
--- a/src/Spout/Common/Singleton.php
+++ b/src/Spout/Common/Singleton.php
@@ -36,6 +36,6 @@ trait Singleton
      */
     protected function init() {}
 
-    final private function __wakeup() {}
-    final private function __clone() {}
+    public function __wakeup() {}
+    public function __clone() {}
 }