diff --git a/src/vs/base/browser/dom.ts b/src/vs/base/browser/dom.ts
index e39ade1ff36..0d6a8f3709b 100644
--- a/src/vs/base/browser/dom.ts
+++ b/src/vs/base/browser/dom.ts
@@ -33,7 +33,7 @@ export const { registerWindow, getWindows, getWindowsCount, getWindowId, onDidRe
 	const mainWindow = window as CodeWindow;
 	if (typeof mainWindow.vscodeWindowId !== 'number') {
 		Object.defineProperty(window, 'vscodeWindowId', {
-			get: () => -1
+			get: () => 1
 		});
 	}
 	windows.set(mainWindow.vscodeWindowId, { window: mainWindow, disposables: new DisposableStore() });
diff --git a/src/vs/platform/native/electron-main/nativeHostMainService.ts b/src/vs/platform/native/electron-main/nativeHostMainService.ts
index 1cd821a33af..29132727162 100644
--- a/src/vs/platform/native/electron-main/nativeHostMainService.ts
+++ b/src/vs/platform/native/electron-main/nativeHostMainService.ts
@@ -150,7 +150,7 @@ export class NativeHostMainService extends Disposable implements INativeHostMain
 	}
 
 	async getActiveWindowId(windowId: number | undefined): Promise<number | undefined> {
-		const activeWindow = BrowserWindow.getFocusedWindow() || this.windowsMainService.getLastActiveWindow();
+		const activeWindow = this.windowsMainService.getFocusedWindow() || this.windowsMainService.getLastActiveWindow();
 		if (activeWindow) {
 			return activeWindow.id;
 		}
diff --git a/src/vs/workbench/services/auxiliaryWindow/browser/auxiliaryWindowService.ts b/src/vs/workbench/services/auxiliaryWindow/browser/auxiliaryWindowService.ts
index 67d0d81e1bf..ecf390dda1b 100644
--- a/src/vs/workbench/services/auxiliaryWindow/browser/auxiliaryWindowService.ts
+++ b/src/vs/workbench/services/auxiliaryWindow/browser/auxiliaryWindowService.ts
@@ -6,7 +6,7 @@
 import { localize } from 'vs/nls';
 import { mark } from 'vs/base/common/performance';
 import { Emitter, Event } from 'vs/base/common/event';
-import { CodeWindow, Dimension, EventHelper, EventType, addDisposableListener, cloneGlobalStylesheets, copyAttributes, createMetaElement, getActiveWindow, getClientArea, isGlobalStylesheet, position, registerWindow, sharedMutationObserver, size, trackAttributes } from 'vs/base/browser/dom';
+import { CodeWindow, Dimension, EventHelper, EventType, addDisposableListener, cloneGlobalStylesheets, copyAttributes, createMetaElement, getActiveWindow, getClientArea, getWindowId, isGlobalStylesheet, position, registerWindow, sharedMutationObserver, size, trackAttributes } from 'vs/base/browser/dom';
 import { Disposable, DisposableStore, IDisposable, toDisposable } from 'vs/base/common/lifecycle';
 import { InstantiationType, registerSingleton } from 'vs/platform/instantiation/common/extensions';
 import { createDecorator } from 'vs/platform/instantiation/common/instantiation';
@@ -62,7 +62,7 @@ export class BrowserAuxiliaryWindowService extends Disposable implements IAuxili
 
 	private static readonly DEFAULT_SIZE = { width: 800, height: 600 };
 
-	private static WINDOW_IDS = 0;
+	private static WINDOW_IDS = getWindowId(window) + 1; // start from the main window ID + 1
 
 	private readonly _onDidOpenAuxiliaryWindow = this._register(new Emitter<IAuxiliaryWindowOpenEvent>());
 	readonly onDidOpenAuxiliaryWindow = this._onDidOpenAuxiliaryWindow.event;