diff --git a/src/badge.ts b/src/badge.ts
new file mode 100644
index 0000000000..e54088b587
--- /dev/null
+++ b/src/badge.ts
@@ -0,0 +1,42 @@
+import { app, ipcMain, type IpcMainEvent, nativeImage } from "electron";
+
+import { _t } from "./language-helper.js";
+
+// Handles calculating the correct "badge" for the window, for notifications and error states.
+// Tray icon updates are handled in tray.ts
+
+if (process.platform === "win32") {
+    // We only use setOverlayIcon on Windows as it's only supported on that platform, but has good support
+    // from all the Windows variants we support.
+    // https://www.electronjs.org/docs/latest/api/browser-window#winsetoverlayiconoverlay-description-windows
+    ipcMain.on(
+        "setBadgeCount",
+        function (_ev: IpcMainEvent, count: number, imageBuffer?: Buffer, isError?: boolean): void {
+            if (count === 0) {
+                // Flash frame is set to true in ipc.ts "loudNotification"
+                global.mainWindow?.flashFrame(false);
+            }
+            if (imageBuffer) {
+                global.mainWindow?.setOverlayIcon(
+                    nativeImage.createFromBuffer(Buffer.from(imageBuffer)),
+                    isError
+                        ? _t("icon_overlay|description_error")
+                        : _t("icon_overlay|description_notifications", { count }),
+                );
+            } else {
+                global.mainWindow?.setOverlayIcon(null, "");
+            }
+        },
+    );
+} else {
+    // only set badgeCount on Mac/Linux, the docs say that only those platforms support it but turns out Electron
+    // has some Windows support too, and in some Windows environments this leads to two badges rendering atop
+    // each other. See https://github.com/vector-im/element-web/issues/16942
+    ipcMain.on("setBadgeCount", function (_ev: IpcMainEvent, count: number): void {
+        if (count === 0) {
+            // Flash frame is set to true in ipc.ts "loudNotification"
+            global.mainWindow?.flashFrame(false);
+        }
+        app.badgeCount = count;
+    });
+}
diff --git a/src/electron-main.ts b/src/electron-main.ts
index 0241b3be6f..3e02206a77 100644
--- a/src/electron-main.ts
+++ b/src/electron-main.ts
@@ -23,6 +23,7 @@ import minimist from "minimist";
 import "./ipc.js";
 import "./seshat.js";
 import "./settings.js";
+import "./badge.js";
 import * as tray from "./tray.js";
 import Store from "./store.js";
 import { buildMenuTemplate } from "./vectormenu.js";