diff --git a/OSBindings/Qt/main.cpp b/OSBindings/Qt/main.cpp
index 59912a79f..89cbb1940 100644
--- a/OSBindings/Qt/main.cpp
+++ b/OSBindings/Qt/main.cpp
@@ -17,7 +17,10 @@ int main(int argc, char *argv[])
 	// TODO: something with QCommandLineParser to accept a file to launch.
 
 	QApplication a(argc, argv);
-	MainWindow w;
-	w.show();
+
+	MainWindow *w = new MainWindow();
+	w->setAttribute(Qt::WA_DeleteOnClose);
+	w->show();
+
 	return a.exec();
 }
diff --git a/OSBindings/Qt/mainwindow.cpp b/OSBindings/Qt/mainwindow.cpp
index fb5eec284..7cf8b491c 100644
--- a/OSBindings/Qt/mainwindow.cpp
+++ b/OSBindings/Qt/mainwindow.cpp
@@ -51,6 +51,9 @@ MainWindow::~MainWindow() {
 	// to write to the audioOutput while it is being shut down.
 	timer.reset();
 
+	// Shut down the scan target while it still has a context for cleanup.
+	ui->openGLWidget->stop();
+
 	// Stop the audio output, and its thread.
 	if(audioOutput) {
 		audioThread.performAsync([this] {
@@ -71,6 +74,7 @@ void MainWindow::closeEvent(QCloseEvent *event) {
 	// i.e. assume they were closing that document, not the application.
 //	if(mainWindowCount == 1 && machine) {
 //		MainWindow *const other = new MainWindow;
+//		other->setAttribute(Qt::WA_DeleteOnClose);
 //		other->show();
 //	}
 	QMainWindow::closeEvent(event);
@@ -103,6 +107,7 @@ void MainWindow::createActions() {
 
 		MainWindow *other = new MainWindow;
 		other->tile(this);
+		other->setAttribute(Qt::WA_DeleteOnClose);
 		other->show();
 	});
 	fileMenu->addAction(newAct);
@@ -119,6 +124,7 @@ void MainWindow::createActions() {
 			if(machine) {
 				MainWindow *const other = new MainWindow(fileName);
 				other->tile(this);
+				other->setAttribute(Qt::WA_DeleteOnClose);
 				other->show();
 			} else {
 				launchFile(fileName);
diff --git a/OSBindings/Qt/scantargetwidget.cpp b/OSBindings/Qt/scantargetwidget.cpp
index a9aab5e32..7663e4f4b 100644
--- a/OSBindings/Qt/scantargetwidget.cpp
+++ b/OSBindings/Qt/scantargetwidget.cpp
@@ -75,3 +75,9 @@ void ScanTargetWidget::setScanProducer(MachineTypes::ScanProducer *producer) {
 	this->producer = producer;
 	repaint();
 }
+
+void ScanTargetWidget::stop() {
+	makeCurrent();
+	scanTarget.reset();
+	isConnected = false;
+}
diff --git a/OSBindings/Qt/scantargetwidget.h b/OSBindings/Qt/scantargetwidget.h
index 520df2153..17a4f7c0c 100644
--- a/OSBindings/Qt/scantargetwidget.h
+++ b/OSBindings/Qt/scantargetwidget.h
@@ -18,6 +18,8 @@ class ScanTargetWidget : public QOpenGLWidget
 		// handed a suitable scan target as soon as one exists.
 		void setScanProducer(MachineTypes::ScanProducer *);
 
+		void stop();
+
 	protected:
 		void initializeGL() override;
 		void resizeGL(int w, int h) override;