diff --git a/cli.ts b/cli.ts
index 8c7716dc..9e942c29 100644
--- a/cli.ts
+++ b/cli.ts
@@ -57,14 +57,14 @@ const main = async (): Promise<void> => {
 		return process.exit(0);
 	}
 
-	const webviewServer = new WebviewServer();
-	const server = new MainServer(webviewServer, args);
-	// The main server inserts webview server address to the root HTML, so we'll
-	// need to wait for it to listen otherwise the address will be null.
-	await webviewServer.listen(typeof args["webview-port"] !== "undefined" && parseInt(args["webview-port"], 10) || 8444);
-	await server.listen(typeof args.port !== "undefined" && parseInt(args.port, 10) || 8443);
-	console.log(`Main server serving ${server.address}`);
-	console.log(`Webview server serving ${webviewServer.address}`);
+	const webviewServer = new WebviewServer(typeof args["webview-port"] !== "undefined" && parseInt(args["webview-port"], 10) || 8444);
+	const server = new MainServer(typeof args.port !== "undefined" && parseInt(args.port, 10) || 8443, webviewServer, args);
+	const [webviewAddress, serverAddress] = await Promise.all([
+		webviewServer.listen(),
+		server.listen()
+	]);
+	console.log(`Main server serving ${serverAddress}`);
+	console.log(`Webview server serving ${webviewAddress}`);
 };
 
 main().catch((error) => {
diff --git a/server.ts b/server.ts
index 2d4f9699..cc5d2a09 100644
--- a/server.ts
+++ b/server.ts
@@ -56,7 +56,9 @@ export abstract class Server {
 	// The underlying web server.
 	protected readonly server: http.Server;
 
-	public constructor() {
+	private listenPromise: Promise<string> | undefined;
+
+	public constructor(private readonly port: number) {
 		this.server = http.createServer(async (request, response): Promise<void> => {
 			try {
 				if (request.method !== "GET") {
@@ -89,14 +91,19 @@ export abstract class Server {
 		requestPath: string,
 	): Promise<[string | Buffer, http.OutgoingHttpHeaders]>;
 
-	public listen(port: number): Promise<void> {
-		return new Promise((resolve, reject) => {
-			this.server.on("error", reject);
-			this.server.listen(port, resolve);
-		});
+	public listen(): Promise<string> {
+		if (!this.listenPromise) {
+			this.listenPromise = new Promise((resolve, reject) => {
+				this.server.on("error", reject);
+				this.server.listen(this.port, () => {
+					resolve(this.address());
+				});
+			});
+		}
+		return this.listenPromise;
 	}
 
-	public get address(): string {
+	public address(): string {
 		const address = this.server.address();
 		const endpoint = typeof address !== "string"
 			? ((address.address === "::" ? "localhost" : address.address) + ":" + address.port)
@@ -121,8 +128,8 @@ export class MainServer extends Server {
 
 	private readonly services = new ServiceCollection();
 
-	public constructor(private readonly webviewServer: WebviewServer, args: ParsedArgs) {
-		super();
+	public constructor(port: number, private readonly webviewServer: WebviewServer, args: ParsedArgs) {
+		super(port);
 
 		this.server.on("upgrade", async (request, socket) => {
 			const protocol = this.createProtocol(request, socket);
@@ -175,7 +182,7 @@ export class MainServer extends Server {
 			const remoteAuthority = request.headers.host as string;
 			const transformer = getUriTransformer(remoteAuthority);
 
-			const webviewEndpoint = this.webviewServer.address;
+			const webviewEndpoint = await this.webviewServer.listen();
 
 			const cwd = process.env.VSCODE_CWD || process.cwd();
 			const workspacePath = parsedUrl.query.workspace as string | undefined;