diff --git a/src/js/service/BeforeUnloadService.js b/src/js/service/BeforeUnloadService.js
index a0c28aed..85521fe8 100644
--- a/src/js/service/BeforeUnloadService.js
+++ b/src/js/service/BeforeUnloadService.js
@@ -6,15 +6,38 @@
   };
 
   ns.BeforeUnloadService.prototype.init = function () {
+    if (pskl.utils.Environment.detectNodeWebkit()) {
+      // Add a dedicated listener to window 'close' event in nwjs environment.
+      var win = require('nw.gui').Window.get();
+      win.on('close', this.onNwWindowClose.bind(this, win));
+    }
+
     window.addEventListener('beforeunload', this.onBeforeUnload.bind(this));
   };
 
+  /**
+   * In nw.js environment "onbeforeunload" is not triggered when closing the window.
+   * Polyfill the behavior here.
+   */
+  ns.BeforeUnloadService.prototype.onNwWindowClose = function (win) {
+    var msg = this.onBeforeUnload();
+    if (msg) {
+      if (!window.confirm(msg)) {
+        return false;
+      }
+    }
+    win.close(true);
+  };
+
   ns.BeforeUnloadService.prototype.onBeforeUnload = function (evt) {
     pskl.app.backupService.backup();
     if (pskl.app.savedStatusService.isDirty()) {
       var confirmationMessage = 'Your Piskel seems to have unsaved changes';
 
-      (evt || window.event).returnValue = confirmationMessage;
+      evt = evt || window.event;
+      if (evt) {
+        evt.returnValue = confirmationMessage;
+      }
       return confirmationMessage;
     }
   };