diff --git a/.gitignore b/.gitignore
index 1531bdf..7ad9e67 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,9 @@
 node_modules
+build
 dist
 .docs
 .coverage
+node_modules
 package-lock.json
 yarn.lock
+.vscode
diff --git a/package.json b/package.json
index b33e551..0a9b55e 100644
--- a/package.json
+++ b/package.json
@@ -189,10 +189,9 @@
     "uint8arraylist": "^2.3.2"
   },
   "devDependencies": {
-    "aegir": "^37.2.0",
+    "aegir": "^38.1.7",
     "it-all": "^2.0.0",
     "it-map": "^2.0.0",
-    "it-pair": "^2.0.2",
     "it-pipe": "^2.0.2",
     "p-defer": "^4.0.0",
     "uint8arrays": "^4.0.2"
diff --git a/src/array-equals.ts b/src/array-equals.ts
index 21db488..e94499a 100644
--- a/src/array-equals.ts
+++ b/src/array-equals.ts
@@ -21,8 +21,8 @@
  * Verify if two arrays of non primitive types with the "equals" function are equal.
  * Compatible with multiaddr, peer-id and others.
  */
-export function arrayEquals (a: any[], b: any[]) {
-  const sort = (a: any, b: any) => a.toString().localeCompare(b.toString())
+export function arrayEquals (a: any[], b: any[]): boolean {
+  const sort = (a: any, b: any): number => a.toString().localeCompare(b.toString())
 
   if (a.length !== b.length) {
     return false
diff --git a/src/ip-port-to-multiaddr.ts b/src/ip-port-to-multiaddr.ts
index 35144d0..bb80dcb 100644
--- a/src/ip-port-to-multiaddr.ts
+++ b/src/ip-port-to-multiaddr.ts
@@ -1,5 +1,5 @@
 import { logger } from '@libp2p/logger'
-import { multiaddr } from '@multiformats/multiaddr'
+import { Multiaddr, multiaddr } from '@multiformats/multiaddr'
 import { CodeError } from '@libp2p/interfaces/errors'
 import { Address4, Address6 } from '@achingbrain/ip-address'
 
@@ -14,7 +14,7 @@ export const Errors = {
 /**
  * Transform an IP, Port pair into a multiaddr
  */
-export function ipPortToMultiaddr (ip: string, port: number | string) {
+export function ipPortToMultiaddr (ip: string, port: number | string): Multiaddr {
   if (typeof ip !== 'string') {
     throw new CodeError(`invalid ip provided: ${ip}`, Errors.ERR_INVALID_IP_PARAMETER) // eslint-disable-line @typescript-eslint/restrict-template-expressions
   }
diff --git a/src/multiaddr/is-loopback.ts b/src/multiaddr/is-loopback.ts
index d676a66..d66f545 100644
--- a/src/multiaddr/is-loopback.ts
+++ b/src/multiaddr/is-loopback.ts
@@ -4,7 +4,7 @@ import type { Multiaddr } from '@multiformats/multiaddr'
 /**
  * Check if a given multiaddr is a loopback address.
  */
-export function isLoopback (ma: Multiaddr) {
+export function isLoopback (ma: Multiaddr): boolean {
   const { address } = ma.nodeAddress()
 
   return isLoopbackAddr(address)
diff --git a/src/multiaddr/is-private.ts b/src/multiaddr/is-private.ts
index 54e8072..4d8f416 100644
--- a/src/multiaddr/is-private.ts
+++ b/src/multiaddr/is-private.ts
@@ -4,7 +4,7 @@ import isIpPrivate from 'private-ip'
 /**
  * Check if a given multiaddr has a private address.
  */
-export function isPrivate (ma: Multiaddr) {
+export function isPrivate (ma: Multiaddr): boolean {
   const { address } = ma.nodeAddress()
 
   return Boolean(isIpPrivate(address))
diff --git a/src/stream-to-ma-conn.ts b/src/stream-to-ma-conn.ts
index 2eeb28d..941f0a0 100644
--- a/src/stream-to-ma-conn.ts
+++ b/src/stream-to-ma-conn.ts
@@ -39,7 +39,7 @@ export interface StreamProperties {
  * Convert a duplex iterable into a MultiaddrConnection.
  * https://github.com/libp2p/interface-transport#multiaddrconnection
  */
-export function streamToMaConnection (props: StreamProperties, options: StreamOptions = {}) {
+export function streamToMaConnection (props: StreamProperties, options: StreamOptions = {}): MultiaddrConnection {
   const { stream, remoteAddr } = props
   const { sink, source } = stream
 
@@ -80,11 +80,11 @@ export function streamToMaConnection (props: StreamProperties, options: StreamOp
     }
   }
 
-  async function close () {
+  async function close (): Promise<void> {
     if (maConn.timeline.close == null) {
       maConn.timeline.close = Date.now()
     }
-    return await Promise.resolve()
+    await Promise.resolve()
   }
 
   return maConn
diff --git a/test/stream-to-ma-conn.spec.ts b/test/stream-to-ma-conn.spec.ts
index 0e9d52c..1997862 100644
--- a/test/stream-to-ma-conn.spec.ts
+++ b/test/stream-to-ma-conn.spec.ts
@@ -11,7 +11,7 @@ import type { Stream } from '@libp2p/interface-connection'
 import type { Duplex } from 'it-stream-types'
 import type { Uint8ArrayList } from 'uint8arraylist'
 
-function toMuxedStream (stream: Duplex<Uint8ArrayList, Uint8ArrayList | Uint8Array>) {
+function toMuxedStream (stream: Duplex<Uint8ArrayList, Uint8ArrayList | Uint8Array>): Stream {
   const muxedStream: Stream = {
     ...stream,
     close: () => {},