diff --git a/scene.cpp b/scene.cpp
index 1a590ee33c..0b45ae9a3c 100644
--- a/scene.cpp
+++ b/scene.cpp
@@ -100,7 +100,7 @@ Scene::Scene(QObject *parent)
 
 Scene::~Scene()
 {
-    qDeleteAll(m_windows);
+    Q_ASSERT(m_windows.isEmpty());
 }
 
 // returns mask and possibly modified region