diff --git a/effects.h b/effects.h
--- a/effects.h
+++ b/effects.h
@@ -494,7 +494,7 @@
     QVariant data(int role) const override;
 
     void registerThumbnail(AbstractThumbnailItem *item);
-    QHash<WindowThumbnailItem*, QWeakPointer<EffectWindowImpl> > const &thumbnails() const {
+    QHash<WindowThumbnailItem*, QPointer<EffectWindowImpl> > const &thumbnails() const {
         return m_thumbnails;
     }
     QList<DesktopThumbnailItem*> const &desktopThumbnails() const {
@@ -510,7 +510,7 @@
     Toplevel* toplevel;
     Scene::Window* sw; // This one is used only during paint pass.
     QHash<int, QVariant> dataMap;
-    QHash<WindowThumbnailItem*, QWeakPointer<EffectWindowImpl> > m_thumbnails;
+    QHash<WindowThumbnailItem*, QPointer<EffectWindowImpl> > m_thumbnails;
     QList<DesktopThumbnailItem*> m_desktopThumbnails;
     bool managed = false;
     bool waylandClient;
diff --git a/effects.cpp b/effects.cpp
--- a/effects.cpp
+++ b/effects.cpp
@@ -2061,9 +2061,9 @@
 {
     EffectWindow *w = effects->findWindow(item->wId());
     if (w) {
-        m_thumbnails.insert(item, QWeakPointer<EffectWindowImpl>(static_cast<EffectWindowImpl*>(w)));
+        m_thumbnails.insert(item, QPointer<EffectWindowImpl>(static_cast<EffectWindowImpl*>(w)));
     } else {
-        m_thumbnails.insert(item, QWeakPointer<EffectWindowImpl>());
+        m_thumbnails.insert(item, QPointer<EffectWindowImpl>());
     }
 }
 
diff --git a/scene.cpp b/scene.cpp
--- a/scene.cpp
+++ b/scene.cpp
@@ -509,7 +509,7 @@
 void Scene::paintWindowThumbnails(Scene::Window *w, QRegion region, qreal opacity, qreal brightness, qreal saturation)
 {
     EffectWindowImpl *wImpl = static_cast<EffectWindowImpl*>(effectWindow(w));
-    for (QHash<WindowThumbnailItem*, QWeakPointer<EffectWindowImpl> >::const_iterator it = wImpl->thumbnails().constBegin();
+    for (QHash<WindowThumbnailItem*, QPointer<EffectWindowImpl> >::const_iterator it = wImpl->thumbnails().constBegin();
             it != wImpl->thumbnails().constEnd();
             ++it) {
         if (it.value().isNull()) {