diff --git a/src/main/java/de/neemann/digital/builder/ATF150x/ATFDialog.java b/src/main/java/de/neemann/digital/builder/ATF150x/ATFDialog.java
index 5949fe130..6bc27f086 100644
--- a/src/main/java/de/neemann/digital/builder/ATF150x/ATFDialog.java
+++ b/src/main/java/de/neemann/digital/builder/ATF150x/ATFDialog.java
@@ -66,7 +66,7 @@ public class ATFDialog extends JDialog {
                     public void windowClosed(WindowEvent e) {
                         if (atmisp.isAlive()) {
                             SwingUtilities.invokeLater(() -> {
-                                JOptionPane.showMessageDialog(null,
+                                JOptionPane.showMessageDialog(parent,
                                         Lang.get("msg_ATMISPIsStillRunning"));
                                 atmisp.terminate();
                             });