diff --git a/src/vs/workbench/api/common/extHostWebview.ts b/src/vs/workbench/api/common/extHostWebview.ts
index 763f79dc5f6..6526b1361d4 100644
--- a/src/vs/workbench/api/common/extHostWebview.ts
+++ b/src/vs/workbench/api/common/extHostWebview.ts
@@ -18,7 +18,7 @@ import { Disposable } from './extHostTypes';
 type IconPath = URI | { light: URI, dark: URI };
 
 export class ExtHostWebview implements vscode.Webview {
-	private _html: string;
+	private _html: string = '';
 	private _isDisposed: boolean = false;
 	private _hasCalledAsWebviewUri = false;
 
diff --git a/src/vs/workbench/contrib/webview/browser/webviewService.ts b/src/vs/workbench/contrib/webview/browser/webviewService.ts
index 0b8c5b01c69..44610b046b8 100644
--- a/src/vs/workbench/contrib/webview/browser/webviewService.ts
+++ b/src/vs/workbench/contrib/webview/browser/webviewService.ts
@@ -18,7 +18,7 @@ export class WebviewService implements IWebviewService {
 	constructor(
 		@IInstantiationService private readonly _instantiationService: IInstantiationService,
 	) {
-		this._instantiationService.createInstance(WebviewThemeDataProvider);
+		this._webviewThemeDataProvider = this._instantiationService.createInstance(WebviewThemeDataProvider);
 	}
 
 	createWebview(