diff --git a/electron/main.js b/electron/main.js
index 134c29e..6d707bd 100644
--- a/electron/main.js
+++ b/electron/main.js
@@ -1,4 +1,4 @@
-const { app, BrowserWindow, session, shell, desktopCapturer, autoUpdater } = require('electron');
+const { app, BrowserWindow, session, shell, desktopCapturer, autoUpdater, dialog } = require('electron');
 const path = require('path');
 const { setupAdBlocker } = require('./ad-blocker');
 
@@ -99,6 +99,27 @@ function createWindow() {
       shell.openExternal(url);
     }
   });
+
+  // Warn before closing if a stream is active
+  let forceClose = false;
+  mainWindow.on('close', (event) => {
+    if (forceClose) return;
+    event.preventDefault();
+    mainWindow.webContents.executeJavaScript(
+      `Array.from(document.querySelectorAll('video')).some(v => v.srcObject?.active)`
+    ).then((isStreaming) => {
+      if (!isStreaming) { forceClose = true; mainWindow.close(); return; }
+      const result = dialog.showMessageBoxSync(mainWindow, {
+        type: 'warning',
+        buttons: ['Beenden', 'Abbrechen'],
+        defaultId: 1,
+        cancelId: 1,
+        title: 'Stream laeuft noch!',
+        message: 'Ein Stream ist noch aktiv.\nBeim Beenden wird der Stream gestoppt.',
+      });
+      if (result === 0) { forceClose = true; mainWindow.close(); }
+    }).catch(() => { forceClose = true; mainWindow.close(); });
+  });
 }
 
 app.whenReady().then(() => {