diff --git a/package.json b/package.json
index 21b27e2..cd0b683 100644
--- a/package.json
+++ b/package.json
@@ -154,7 +154,7 @@
   "devDependencies": {
     "@libp2p/interface-mocks": "^8.0.1",
     "@libp2p/interface-transport-compliance-tests": "^3.0.0",
-    "aegir": "^37.7.3",
+    "aegir": "^38.1.0",
     "it-all": "^2.0.0",
     "it-pipe": "^2.0.3",
     "p-defer": "^4.0.0",
diff --git a/src/index.ts b/src/index.ts
index 50aed20..243452a 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -92,7 +92,7 @@ class TCP implements Transport {
     return true
   }
 
-  get [Symbol.toStringTag] () {
+  get [Symbol.toStringTag] (): string {
     return '@libp2p/tcp'
   }
 
@@ -114,7 +114,7 @@ class TCP implements Transport {
       metrics: this.metrics?.dialerEvents
     })
 
-    const onAbort = () => {
+    const onAbort = (): void => {
       maConn.close().catch(err => {
         log.error('Error closing maConn after abort', err)
       })
@@ -138,7 +138,7 @@ class TCP implements Transport {
     return conn
   }
 
-  async _connect (ma: Multiaddr, options: TCPDialOptions) {
+  async _connect (ma: Multiaddr, options: TCPDialOptions): Promise<Socket> {
     if (options.signal?.aborted === true) {
       throw new AbortError()
     }
@@ -151,14 +151,14 @@ class TCP implements Transport {
       log('dialing %j', cOpts)
       const rawSocket = net.connect(cOpts)
 
-      const onError = (err: Error) => {
+      const onError = (err: Error): void => {
         err.message = `connection error ${cOptsStr}: ${err.message}`
         this.metrics?.dialerEvents.increment({ error: true })
 
         done(err)
       }
 
-      const onTimeout = () => {
+      const onTimeout = (): void => {
         log('connection timeout %s', cOptsStr)
         this.metrics?.dialerEvents.increment({ timeout: true })
 
@@ -167,20 +167,20 @@ class TCP implements Transport {
         rawSocket.emit('error', err)
       }
 
-      const onConnect = () => {
+      const onConnect = (): void => {
         log('connection opened %j', cOpts)
         this.metrics?.dialerEvents.increment({ connect: true })
         done()
       }
 
-      const onAbort = () => {
+      const onAbort = (): void => {
         log('connection aborted %j', cOpts)
         this.metrics?.dialerEvents.increment({ abort: true })
         rawSocket.destroy()
         done(new AbortError())
       }
 
-      const done = (err?: any) => {
+      const done = (err?: any): void => {
         rawSocket.removeListener('error', onError)
         rawSocket.removeListener('timeout', onTimeout)
         rawSocket.removeListener('connect', onConnect)
@@ -190,7 +190,7 @@ class TCP implements Transport {
         }
 
         if (err != null) {
-          return reject(err)
+          reject(err); return
         }
 
         resolve(rawSocket)
diff --git a/src/listener.ts b/src/listener.ts
index 7ca3ff3..617f08a 100644
--- a/src/listener.ts
+++ b/src/listener.ts
@@ -19,7 +19,7 @@ const log = logger('libp2p:tcp:listener')
 /**
  * Attempts to close the given maConn. If a failure occurs, it will be logged
  */
-async function attemptClose (maConn: MultiaddrConnection) {
+async function attemptClose (maConn: MultiaddrConnection): Promise<void> {
   try {
     await maConn.close()
   } catch (err) {
@@ -54,7 +54,7 @@ export interface TCPListenerMetrics {
   events: CounterGroup
 }
 
-type Status = {started: false} | {
+type Status = { started: false } | {
   started: true
   listeningAddr: Multiaddr
   peerId: string | null
@@ -150,7 +150,7 @@ export class TCPListener extends EventEmitter<ListenerEvents> implements Listene
       })
   }
 
-  private onSocket (socket: net.Socket) {
+  private onSocket (socket: net.Socket): void {
     // Avoid uncaught errors caused by unstable connections
     socket.on('error', err => {
       log('socket error', err)
@@ -230,7 +230,7 @@ export class TCPListener extends EventEmitter<ListenerEvents> implements Listene
     }
   }
 
-  getAddrs () {
+  getAddrs (): Multiaddr[] {
     if (!this.status.started) {
       return []
     }
@@ -262,7 +262,7 @@ export class TCPListener extends EventEmitter<ListenerEvents> implements Listene
     return addrs.map(ma => peerId != null ? ma.encapsulate(`/p2p/${peerId}`) : ma)
   }
 
-  async listen (ma: Multiaddr) {
+  async listen (ma: Multiaddr): Promise<void> {
     if (this.status.started) {
       throw Error('server is already listening')
     }
@@ -280,9 +280,9 @@ export class TCPListener extends EventEmitter<ListenerEvents> implements Listene
     await this.netListen()
   }
 
-  async close () {
+  async close (): Promise<void> {
     await Promise.all(
-      Array.from(this.connections.values()).map(async maConn => await attemptClose(maConn))
+      Array.from(this.connections.values()).map(async maConn => { await attemptClose(maConn) })
     )
 
     // netClose already checks if server.listening
diff --git a/src/socket-to-conn.ts b/src/socket-to-conn.ts
index 6369f90..611c456 100644
--- a/src/socket-to-conn.ts
+++ b/src/socket-to-conn.ts
@@ -26,7 +26,7 @@ interface ToConnectionOptions {
  * Convert a socket into a MultiaddrConnection
  * https://github.com/libp2p/interface-transport#multiaddrconnection
  */
-export const toMultiaddrConnection = (socket: Socket, options: ToConnectionOptions) => {
+export const toMultiaddrConnection = (socket: Socket, options: ToConnectionOptions): MultiaddrConnection => {
   const metrics = options.metrics
   const metricPrefix = options.metricPrefix ?? ''
   const inactivityTimeout = options.socketInactivityTimeout ?? SOCKET_TIMEOUT
diff --git a/src/utils.ts b/src/utils.ts
index 502c9b1..e5931c6 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -25,19 +25,19 @@ export function multiaddrToNetConfig (addr: Multiaddr): NetConfig {
   return addr.toOptions()
 }
 
-export function getMultiaddrs (proto: 'ip4' | 'ip6', ip: string, port: number) {
-  const toMa = (ip: string) => multiaddr(`/${proto}/${ip}/tcp/${port}`)
+export function getMultiaddrs (proto: 'ip4' | 'ip6', ip: string, port: number): Multiaddr[] {
+  const toMa = (ip: string): Multiaddr => multiaddr(`/${proto}/${ip}/tcp/${port}`)
   return (isAnyAddr(ip) ? getNetworkAddrs(ProtoFamily[proto]) : [ip]).map(toMa)
 }
 
-export function isAnyAddr (ip: string) {
+export function isAnyAddr (ip: string): boolean {
   return ['0.0.0.0', '::'].includes(ip)
 }
 
 const networks = os.networkInterfaces()
 
-function getNetworkAddrs (family: string) {
-  const addresses = []
+function getNetworkAddrs (family: string): string[] {
+  const addresses: string[] = []
 
   for (const [, netAddrs] of Object.entries(networks)) {
     if (netAddrs != null) {
diff --git a/test/connection.spec.ts b/test/connection.spec.ts
index 254826a..8712885 100644
--- a/test/connection.spec.ts
+++ b/test/connection.spec.ts
@@ -21,7 +21,7 @@ describe('valid localAddr and remoteAddr', () => {
     let handled: (conn: Connection) => void
     const handlerPromise = new Promise<Connection>(resolve => { handled = resolve })
 
-    const handler = (conn: Connection) => handled(conn)
+    const handler = (conn: Connection): void => { handled(conn) }
 
     // Create a listener with the handler
     const listener = transport.createListener({
@@ -52,7 +52,7 @@ describe('valid localAddr and remoteAddr', () => {
     let handled: (conn: Connection) => void
     const handlerPromise = new Promise<Connection>(resolve => { handled = resolve })
 
-    const handler = (conn: Connection) => handled(conn)
+    const handler = (conn: Connection): void => { handled(conn) }
 
     // Create a listener with the handler
     const listener = transport.createListener({
@@ -76,7 +76,7 @@ describe('valid localAddr and remoteAddr', () => {
 
     // Close the dialer with two simultaneous calls to `close`
     await Promise.race([
-      new Promise((resolve, reject) => setTimeout(() => reject(new Error('Timed out waiting for connection close')), 500)),
+      new Promise((resolve, reject) => setTimeout(() => { reject(new Error('Timed out waiting for connection close')) }, 500)),
       await Promise.all([
         dialerConn.close(),
         dialerConn.close()
diff --git a/test/listen-dial.spec.ts b/test/listen-dial.spec.ts
index ded447d..cd884de 100644
--- a/test/listen-dial.spec.ts
+++ b/test/listen-dial.spec.ts
@@ -259,7 +259,7 @@ describe('dial', () => {
         // let multistream select finish before closing
         setTimeout(() => {
           void conn.close()
-            .then(() => handled())
+            .then(() => { handled() })
         }, 100)
       },
       upgrader
@@ -272,7 +272,7 @@ describe('dial', () => {
       upgrader
     })
     const stream = await conn.newStream([protocol])
-    await pipe(stream)
+    pipe(stream)
 
     await handledPromise
     await conn.close()
@@ -340,7 +340,7 @@ describe('dial', () => {
 
       // take a long time to give us time to abort the dial
       await new Promise<void>((resolve) => {
-        setTimeout(() => resolve(), 100)
+        setTimeout(() => { resolve() }, 100)
       })
     }
 
@@ -352,7 +352,7 @@ describe('dial', () => {
     const abortController = new AbortController()
 
     // abort once the upgrade process has started
-    void maConnPromise.promise.then(() => abortController.abort())
+    void maConnPromise.promise.then(() => { abortController.abort() })
 
     await expect(transport.dial(ma, {
       upgrader,
diff --git a/test/max-connections-close.spec.ts b/test/max-connections-close.spec.ts
index c9cb926..1cb51c4 100644
--- a/test/max-connections-close.spec.ts
+++ b/test/max-connections-close.spec.ts
@@ -45,7 +45,7 @@ describe('close server on maxConnections', () => {
       return socket
     }
 
-    async function assertConnectedSocket (i: number) {
+    async function assertConnectedSocket (i: number): Promise<net.Socket> {
       const socket = createSocket()
 
       await new Promise<void>((resolve, reject) => {
@@ -61,7 +61,7 @@ describe('close server on maxConnections', () => {
       return socket
     }
 
-    async function assertRefusedSocket (i: number) {
+    async function assertRefusedSocket (i: number): Promise<void> {
       const socket = createSocket()
 
       await new Promise<void>((resolve, reject) => {
@@ -79,7 +79,7 @@ describe('close server on maxConnections', () => {
       })
     }
 
-    async function assertServerConnections (connections: number) {
+    async function assertServerConnections (connections: number): Promise<void> {
       // Expect server connections but allow time for sockets to connect or disconnect
       for (let i = 0; i < 100; i++) {
         // eslint-disable-next-line @typescript-eslint/dot-notation
diff --git a/test/socket-to-conn.spec.ts b/test/socket-to-conn.spec.ts
index 49c339f..6b63501 100644
--- a/test/socket-to-conn.spec.ts
+++ b/test/socket-to-conn.spec.ts
@@ -5,7 +5,7 @@ import { toMultiaddrConnection } from '../src/socket-to-conn.js'
 import os from 'os'
 import type { ServerOpts, SocketConstructorOpts } from 'net'
 
-async function setup (opts?: { server?: ServerOpts, client?: SocketConstructorOpts }) {
+async function setup (opts?: { server?: ServerOpts, client?: SocketConstructorOpts }): Promise<{ server: Server, serverSocket: Socket, clientSocket: Socket }> {
   const serverListening = defer()
 
   const server = createServer(opts?.server)