diff --git a/src/app/application.cpp b/src/app/application.cpp
index aeee2c7cd..3b1ff7b1a 100644
--- a/src/app/application.cpp
+++ b/src/app/application.cpp
@@ -33,6 +33,7 @@
 #include <QLibraryInfo>
 #include <QSysInfo>
 #include <QProcess>
+#include <QAtomicInt>
 
 #ifndef DISABLE_GUI
 #include "gui/guiiconprovider.h"
@@ -547,11 +548,9 @@ void Application::cleanup()
 #ifndef DISABLE_GUI
 #ifdef Q_OS_WIN
     // cleanup() can be called multiple times during shutdown. We only need it once.
-    static bool alreadyDone = false;
-
-    if (alreadyDone)
+    static QAtomicInt alreadyDone;
+    if (!alreadyDone.testAndSetAcquire(0, 1))
         return;
-    alreadyDone = true;
 #endif // Q_OS_WIN
 
     // Hide the window and not leave it on screen as
diff --git a/src/gui/mainwindow.cpp b/src/gui/mainwindow.cpp
index 4306d7c68..25c22b1b7 100644
--- a/src/gui/mainwindow.cpp
+++ b/src/gui/mainwindow.cpp
@@ -678,12 +678,12 @@ void MainWindow::cleanup()
 #if (defined(Q_OS_WIN) || defined(Q_OS_MAC))
     m_programUpdateTimer->stop();
 #endif
-    delete m_searchFilter;
+
     delete m_searchFilterAction;
-    delete m_tabs; // this seems enough to also delete all contained widgets
-    delete m_statusBar;
-    delete m_pwr;
-    delete m_toolbarMenu;
+
+    // remove all child widgets
+    while (QWidget *w = findChild<QWidget *>())
+        delete w;
 }
 
 void MainWindow::readSettings()