diff --git a/src/vs/workbench/contrib/webview/browser/pre/host.js b/src/vs/workbench/contrib/webview/browser/pre/host.js
index 99b4ecbb3a89d5e6824d343f2d0714c34b1ceadf..4015cadcc3edc72871b3e501fdb448cd67d7b636 100644
--- a/src/vs/workbench/contrib/webview/browser/pre/host.js
+++ b/src/vs/workbench/contrib/webview/browser/pre/host.js
@@ -90,7 +90,7 @@
 		}
 	}
 
-	window.createWebviewManager({
+	(/** @type {any} */ (window)).createWebviewManager({
 		postMessage: hostMessaging.postMessage.bind(hostMessaging),
 		onMessage: hostMessaging.onMessage.bind(hostMessaging),
 		ready: workerReady,
diff --git a/src/vs/workbench/contrib/webview/browser/pre/main.js b/src/vs/workbench/contrib/webview/browser/pre/main.js
index e42932ecf9f13b9dbc2d2386e9e68c26b28b65c4..3b683f5ea47705b5777f8aac63f1dea3944f68e4 100644
--- a/src/vs/workbench/contrib/webview/browser/pre/main.js
+++ b/src/vs/workbench/contrib/webview/browser/pre/main.js
@@ -11,7 +11,7 @@
  *   focusIframeOnCreate?: boolean,
  *   ready?: Promise<void>,
  *   onIframeLoaded?: (iframe: HTMLIFrameElement) => void,
- *   fakeLoad: boolean,
+ *   fakeLoad?: boolean,
  *   rewriteCSP: (existingCSP: string, endpoint?: string) => string,
  * }} WebviewHost
  */
@@ -605,6 +605,6 @@
 	if (typeof module !== 'undefined') {
 		module.exports = createWebviewManager;
 	} else {
-		window.createWebviewManager = createWebviewManager;
+		(/** @type {any} */ (window)).createWebviewManager = createWebviewManager;
 	}
 }());
diff --git a/src/vs/workbench/contrib/webview/browser/pre/service-worker.js b/src/vs/workbench/contrib/webview/browser/pre/service-worker.js
index 8d26680d73ab40c3c286f32407bfd91f95b21bca..5d043d56ff0c4190659387a22c1bb77926bf838b 100644
--- a/src/vs/workbench/contrib/webview/browser/pre/service-worker.js
+++ b/src/vs/workbench/contrib/webview/browser/pre/service-worker.js
@@ -2,6 +2,8 @@
  *  Copyright (c) Microsoft Corporation. All rights reserved.
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
+/// <reference lib="webworker" />
+
 const VERSION = 1;
 
 const rootPath = self.location.pathname.replace(/\/service-worker.js$/, '');
@@ -273,4 +275,4 @@ async function getOuterIframeClient(webviewId) {
 		const clientUrl = new URL(client.url);
 		return (clientUrl.pathname === `${rootPath}/` || clientUrl.pathname === `${rootPath}/index.html`) && clientUrl.search.match(new RegExp('\\bid=' + webviewId));
 	});
-}
\ No newline at end of file
+}