diff --git a/extensions/css-language-features/client/src/browser/cssClientMain.ts b/extensions/css-language-features/client/src/browser/cssClientMain.ts
index 6f309858f44..8b1d7205fcd 100644
--- a/extensions/css-language-features/client/src/browser/cssClientMain.ts
+++ b/extensions/css-language-features/client/src/browser/cssClientMain.ts
@@ -11,6 +11,9 @@ import { LanguageClient } from 'vscode-languageclient/browser';
 declare const Worker: {
 	new(stringUrl: string): any;
 };
+declare const TextDecoder: {
+	new(encoding?: string): { decode(buffer: ArrayBuffer): string; };
+};
 
 // this method is called when vs code is activated
 export function activate(context: ExtensionContext) {
@@ -21,7 +24,7 @@ export function activate(context: ExtensionContext) {
 			return new LanguageClient(id, name, clientOptions, worker);
 		};
 
-		startClient(context, newLanguageClient, {});
+		startClient(context, newLanguageClient, { TextDecoder });
 
 	} catch (e) {
 		console.log(e);
diff --git a/extensions/css-language-features/client/src/cssClient.ts b/extensions/css-language-features/client/src/cssClient.ts
index d0df1706cd7..4bfa95c8439 100644
--- a/extensions/css-language-features/client/src/cssClient.ts
+++ b/extensions/css-language-features/client/src/cssClient.ts
@@ -17,7 +17,12 @@ const localize = nls.loadMessageBundle();
 
 export type LanguageClientConstructor = (name: string, description: string, clientOptions: LanguageClientOptions) => CommonLanguageClient;
 
-export function startClient(context: ExtensionContext, newLanguageClient: LanguageClientConstructor, runtime: { fs?: RequestService }) {
+export interface Runtime {
+	TextDecoder: { new(encoding?: string): { decode(buffer: ArrayBuffer): string; } };
+	fs?: RequestService;
+}
+
+export function startClient(context: ExtensionContext, newLanguageClient: LanguageClientConstructor, runtime: Runtime) {
 
 	const customDataSource = getCustomDataSource(context.subscriptions);
 
diff --git a/extensions/css-language-features/client/src/node/cssClientMain.ts b/extensions/css-language-features/client/src/node/cssClientMain.ts
index 1c84b2a849f..350e0de02d5 100644
--- a/extensions/css-language-features/client/src/node/cssClientMain.ts
+++ b/extensions/css-language-features/client/src/node/cssClientMain.ts
@@ -6,8 +6,8 @@
 import { getNodeFSRequestService } from './nodeFs';
 import { ExtensionContext, extensions } from 'vscode';
 import { startClient, LanguageClientConstructor } from '../cssClient';
-
 import { ServerOptions, TransportKind, LanguageClientOptions, LanguageClient } from 'vscode-languageclient/node';
+import { TextDecoder } from 'util';
 
 // this method is called when vs code is activated
 export function activate(context: ExtensionContext) {
@@ -34,5 +34,5 @@ export function activate(context: ExtensionContext) {
 		return new LanguageClient(id, name, serverOptions, clientOptions);
 	};
 
-	startClient(context, newLanguageClient, { fs: getNodeFSRequestService() });
+	startClient(context, newLanguageClient, { fs: getNodeFSRequestService(), TextDecoder });
 }
diff --git a/extensions/css-language-features/client/src/requests.ts b/extensions/css-language-features/client/src/requests.ts
index 522745e0137..1b1e70b2d88 100644
--- a/extensions/css-language-features/client/src/requests.ts
+++ b/extensions/css-language-features/client/src/requests.ts
@@ -5,7 +5,7 @@
 
 import { Uri, workspace } from 'vscode';
 import { RequestType, CommonLanguageClient } from 'vscode-languageclient';
-import { TextDecoder } from 'util';
+import { Runtime } from './cssClient';
 
 export namespace FsContentRequest {
 	export const type: RequestType<{ uri: string; encoding?: string; }, string, any, any> = new RequestType('fs/content');
@@ -18,14 +18,14 @@ export namespace FsReadDirRequest {
 	export const type: RequestType<string, [string, FileType][], any, any> = new RequestType('fs/readDir');
 }
 
-export function serveFileSystemRequests(client: CommonLanguageClient, runtime: { fs?: RequestService; }) {
+export function serveFileSystemRequests(client: CommonLanguageClient, runtime: Runtime) {
 	client.onRequest(FsContentRequest.type, (param: { uri: string; encoding?: string; }) => {
 		const uri = Uri.parse(param.uri);
 		if (uri.scheme === 'file' && runtime.fs) {
 			return runtime.fs.getContent(param.uri);
 		}
 		return workspace.fs.readFile(uri).then(buffer => {
-			return new TextDecoder(param.encoding).decode(buffer);
+			return new runtime.TextDecoder(param.encoding).decode(buffer);
 		});
 	});
 	client.onRequest(FsReadDirRequest.type, (uriString: string) => {