diff --git a/packages/api/test/unit/client/httpClient.test.ts b/packages/api/test/unit/client/httpClient.test.ts
index 4371a088eca7..f9961f0b16df 100644
--- a/packages/api/test/unit/client/httpClient.test.ts
+++ b/packages/api/test/unit/client/httpClient.test.ts
@@ -32,7 +32,7 @@ describe("httpClient json client", () => {
       await server.close();
     });
 
-    return {baseUrl: await server.listen(0)};
+    return {baseUrl: await server.listen({port: 0})};
   }
 
   async function getServerWithClient(opts: RouteOptions): Promise<HttpClient> {
diff --git a/packages/api/test/utils/utils.ts b/packages/api/test/utils/utils.ts
index 26c4e5bcfd23..ac160aa45208 100644
--- a/packages/api/test/utils/utils.ts
+++ b/packages/api/test/utils/utils.ts
@@ -21,7 +21,7 @@ export function getTestServer(): {baseUrl: string; server: FastifyInstance} {
 
   before("start server", async () => {
     await new Promise((resolve, reject) => {
-      server.listen(port, function (err, address) {
+      server.listen({port}, function (err, address) {
         if (err !== null && err != undefined) {
           reject(err);
         } else {
diff --git a/packages/beacon-node/src/api/rest/base.ts b/packages/beacon-node/src/api/rest/base.ts
index 6a9419b35f87..045be3836323 100644
--- a/packages/beacon-node/src/api/rest/base.ts
+++ b/packages/beacon-node/src/api/rest/base.ts
@@ -1,5 +1,5 @@
 import qs from "qs";
-import fastify, {FastifyError, FastifyInstance} from "fastify";
+import fastify, {FastifyInstance} from "fastify";
 import fastifyCors from "@fastify/cors";
 import bearerAuthPlugin from "@fastify/bearer-auth";
 import {RouteConfig} from "@lodestar/api/beacon/server";
@@ -59,8 +59,8 @@ export class RestApiServer {
 
     // To parse our ApiError -> statusCode
     server.setErrorHandler((err, req, res) => {
-      if ((err as FastifyError).validation) {
-        void res.status(400).send((err as FastifyError).validation);
+      if (err.validation) {
+        void res.status(400).send(err.validation);
       } else {
         // Convert our custom ApiError into status code
         const statusCode = err instanceof ApiError ? err.statusCode : 500;
@@ -116,7 +116,7 @@ export class RestApiServer {
   async listen(): Promise<void> {
     try {
       const host = this.opts.address;
-      const address = await this.server.listen(this.opts.port, host);
+      const address = await this.server.listen({port: this.opts.port, host});
       this.logger.info("Started REST API server", {address});
       if (!host || !isLocalhostIP(host)) {
         this.logger.warn("REST API server is exposed, ensure untrusted traffic cannot reach this API");
diff --git a/packages/beacon-node/test/unit/executionEngine/http.test.ts b/packages/beacon-node/test/unit/executionEngine/http.test.ts
index 24ea67301b9e..5d82b1f3a230 100644
--- a/packages/beacon-node/test/unit/executionEngine/http.test.ts
+++ b/packages/beacon-node/test/unit/executionEngine/http.test.ts
@@ -38,7 +38,7 @@ describe("ExecutionEngine / http", () => {
       await server.close();
     });
 
-    const baseUrl = await server.listen(0);
+    const baseUrl = await server.listen({port: 0});
 
     executionEngine = initializeExecutionEngine(
       {
diff --git a/packages/beacon-node/test/unit/executionEngine/httpRetry.test.ts b/packages/beacon-node/test/unit/executionEngine/httpRetry.test.ts
index bb5caeb1048a..ee21afb4b02b 100644
--- a/packages/beacon-node/test/unit/executionEngine/httpRetry.test.ts
+++ b/packages/beacon-node/test/unit/executionEngine/httpRetry.test.ts
@@ -43,7 +43,7 @@ describe("ExecutionEngine / http ", () => {
       await server.close();
     });
 
-    baseUrl = await server.listen(0);
+    baseUrl = await server.listen({port: 0});
 
     executionEngine = initializeExecutionEngine(
       {
diff --git a/packages/cli/test/utils/simulation/ExternalSignerServer.ts b/packages/cli/test/utils/simulation/ExternalSignerServer.ts
index 7cec08e01d61..f6d258ddfa00 100644
--- a/packages/cli/test/utils/simulation/ExternalSignerServer.ts
+++ b/packages/cli/test/utils/simulation/ExternalSignerServer.ts
@@ -66,7 +66,7 @@ export class ExternalSignerServer {
 
   async start(): Promise<void> {
     console.log(`Starting external signer server at ${this.url}.`);
-    await this.server.listen(this.port, this.address);
+    await this.server.listen({port: this.port, host: this.address});
     console.log(`Started external signer server at ${this.url}.`);
   }
 
diff --git a/packages/light-client/test/utils/server.ts b/packages/light-client/test/utils/server.ts
index c837a54e15e4..3effdd06e658 100644
--- a/packages/light-client/test/utils/server.ts
+++ b/packages/light-client/test/utils/server.ts
@@ -25,6 +25,6 @@ export async function startServer(
 
   void server.register(fastifyCors, {origin: "*"});
 
-  await server.listen(opts.port, opts.host);
+  await server.listen({port: opts.port, host: opts.host});
   return server;
 }