diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index c11e0d0..c5002ce 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -27,7 +27,7 @@ jobs:
     strategy:
       matrix:
         os: [windows-latest, ubuntu-latest, macos-latest]
-        node: [12, 14]
+        node: [14, 15]
       fail-fast: true
     steps:
       - uses: actions/checkout@v2
diff --git a/package.json b/package.json
index 95683e7..7eb0644 100644
--- a/package.json
+++ b/package.json
@@ -22,9 +22,9 @@
     "extends": "ipfs"
   },
   "scripts": {
+    "prepare": "aegir build --no-bundle",
     "lint": "aegir lint",
     "build": "aegir build",
-    "prepare": "aegir build --no-bundle",
     "test": "aegir test",
     "test:node": "aegir test --target node",
     "test:browser": "aegir test --target browser",
@@ -47,39 +47,43 @@
   },
   "homepage": "https://github.com/libp2p/js-interfaces#readme",
   "dependencies": {
-    "@types/bl": "^2.1.0",
+    "@types/bl": "4.1.0",
     "abort-controller": "^3.0.0",
     "abortable-iterator": "^3.0.0",
-    "chai": "^4.2.0",
+    "chai": "^4.3.4",
     "chai-checkmark": "^1.0.1",
     "debug": "^4.3.1",
-    "delay": "^4.4.0",
+    "delay": "^5.0.0",
     "detect-node": "^2.0.4",
     "dirty-chai": "^2.0.1",
-    "err-code": "^2.0.3",
+    "err-code": "^3.0.1",
     "it-goodbye": "^2.0.2",
     "it-length-prefixed": "^3.1.0",
     "it-pair": "^1.0.0",
     "it-pipe": "^1.1.0",
-    "it-pushable": "^1.4.0",
+    "it-pushable": "^1.4.2",
     "libp2p-crypto": "^0.19.0",
     "libp2p-tcp": "^0.15.0",
     "multiaddr": "^8.1.2",
-    "multibase": "^3.1.1",
-    "multihashes": "^3.1.1",
+    "multibase": "^4.0.2",
+    "multihashes": "^4.0.2",
     "p-defer": "^3.0.0",
     "p-limit": "^3.1.0",
     "p-wait-for": "^3.2.0",
     "peer-id": "^0.14.2",
     "protons": "^2.0.0",
-    "sinon": "^9.2.4",
+    "sinon": "^10.0.0",
     "streaming-iterables": "^5.0.4",
-    "uint8arrays": "^2.0.5"
+    "uint8arrays": "^2.1.3"
   },
   "devDependencies": {
-    "aegir": "^29.2.0",
+    "@types/debug": "^4.1.5",
+    "aegir": "^32.1.0",
+    "cids": "^1.1.6",
+    "events": "^3.3.0",
     "it-handshake": "^1.0.2",
-    "rimraf": "^3.0.2"
+    "rimraf": "^3.0.2",
+    "util": "^0.12.3"
   },
   "contributors": [
     "Alan Shaw <alan.shaw@protocol.ai>",
diff --git a/src/connection/connection.js b/src/connection/connection.js
index be59f0c..afe06c8 100644
--- a/src/connection/connection.js
+++ b/src/connection/connection.js
@@ -230,6 +230,15 @@ class Connection {
 
 module.exports = Connection
 
+/**
+ * @param {multiaddr|undefined} localAddr
+ * @param {PeerId} localPeer
+ * @param {PeerId} remotePeer
+ * @param {(protocols: string | string[]) => Promise<{ stream: import("../stream-muxer/types").MuxedStream; protocol: string; }>} newStream
+ * @param {() => Promise<void>} close
+ * @param {() => import("../stream-muxer/types").MuxedStream[]} getStreams
+ * @param {{ direction: any; timeline: any; multiplexer?: string | undefined; encryption?: string | undefined; }} stat
+ */
 function validateArgs (localAddr, localPeer, remotePeer, newStream, close, getStreams, stat) {
   if (localAddr && !multiaddr.isMultiaddr(localAddr)) {
     throw errCode(new Error('localAddr must be an instance of multiaddr'), 'ERR_INVALID_PARAMETERS')
diff --git a/src/connection/tests/connection.js b/src/connection/tests/connection.js
index 83df518..30e0327 100644
--- a/src/connection/tests/connection.js
+++ b/src/connection/tests/connection.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 
 'use strict'
diff --git a/src/connection/tests/index.js b/src/connection/tests/index.js
index d008297..f159b5b 100644
--- a/src/connection/tests/index.js
+++ b/src/connection/tests/index.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 
 'use strict'
diff --git a/src/content-routing/types.d.ts b/src/content-routing/types.d.ts
new file mode 100644
index 0000000..85c549c
--- /dev/null
+++ b/src/content-routing/types.d.ts
@@ -0,0 +1,11 @@
+export = ContentRouting;
+
+import PeerId from 'peer-id'
+import Multiaddr from 'multiaddr'
+import CID from 'cids'
+
+declare class ContentRouting {
+  constructor (options: Object);
+  provide (cid: CID): Promise<void>;
+  findProviders (cid: CID, options: Object): AsyncIterable<{ id: PeerId, multiaddrs: Multiaddr[] }>;
+}
diff --git a/src/content-routing/types.ts b/src/content-routing/types.ts
deleted file mode 100644
index e69de29..0000000
diff --git a/src/crypto/tests/index.js b/src/crypto/tests/index.js
index d04b0f9..7ff2bc0 100644
--- a/src/crypto/tests/index.js
+++ b/src/crypto/tests/index.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/crypto/types.ts b/src/crypto/types.d.ts
similarity index 100%
rename from src/crypto/types.ts
rename to src/crypto/types.d.ts
diff --git a/src/peer-discovery/tests/index.js b/src/peer-discovery/tests/index.js
index 55dbee7..7283899 100644
--- a/src/peer-discovery/tests/index.js
+++ b/src/peer-discovery/tests/index.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/peer-discovery/types.d.ts b/src/peer-discovery/types.d.ts
new file mode 100644
index 0000000..db383cb
--- /dev/null
+++ b/src/peer-discovery/types.d.ts
@@ -0,0 +1,10 @@
+export = PeerDiscovery;
+
+import events from 'events';
+
+declare class PeerDiscovery extends events.EventEmitter {
+  constructor (options: Object);
+  start (): Promise<void>;
+  stop (): Promise<void>;
+  tag: string;
+}
diff --git a/src/peer-routing/types.d.ts b/src/peer-routing/types.d.ts
new file mode 100644
index 0000000..58ea7a7
--- /dev/null
+++ b/src/peer-routing/types.d.ts
@@ -0,0 +1,10 @@
+export = PeerRouting;
+
+import PeerId from 'peer-id'
+import Multiaddr from 'multiaddr'
+
+declare class PeerRouting {
+  constructor (options?: Object);
+  findPeer (peerId: PeerId, options?: Object): Promise<{ id: PeerId, multiaddrs: Multiaddr[] }>;
+  getClosestPeers(key: Uint8Array, options?: Object): AsyncIterable<{ id: PeerId, multiaddrs: Multiaddr[] }>;
+}
diff --git a/src/pubsub/index.js b/src/pubsub/index.js
index 4fd93c1..f7338ca 100644
--- a/src/pubsub/index.js
+++ b/src/pubsub/index.js
@@ -10,9 +10,7 @@ const { pipe } = require('it-pipe')
 
 const MulticodecTopology = require('../topology/multicodec-topology')
 const { codes } = require('./errors')
-/**
- * @type {typeof import('./message')}
- */
+
 const message = require('./message')
 const PeerStreams = require('./peer-streams')
 const { SignaturePolicy } = require('./signature-policy')
@@ -29,9 +27,9 @@ const {
  * @typedef {import('bl')} BufferList
  * @typedef {import('../stream-muxer/types').MuxedStream} MuxedStream
  * @typedef {import('../connection/connection')} Connection
- * @typedef {import('./message').RPC} RPC
- * @typedef {import('./message').SubOpts} RPCSubOpts
- * @typedef {import('./message').Message} RPCMessage
+ * @typedef {import('./message/types').RPC} RPC
+ * @typedef {import('./message/types').SubOpts} RPCSubOpts
+ * @typedef {import('./message/types').Message} RPCMessage
  * @typedef {import('./signature-policy').SignaturePolicyType} SignaturePolicyType
  */
 
@@ -44,6 +42,16 @@ const {
  * @property {Uint8Array} data
  * @property {Uint8Array} [signature]
  * @property {Uint8Array} [key]
+ *
+ * @typedef {Object} PubsubProperties
+ * @property {string} debugName - log namespace
+ * @property {Array<string>|string} multicodecs - protocol identificers to connect
+ * @property {Libp2p} libp2p
+ *
+ * @typedef {Object} PubsubOptions
+ * @property {SignaturePolicyType} [globalSignaturePolicy = SignaturePolicy.StrictSign] - defines how signatures should be handled
+ * @property {boolean} [canRelayMessage = false] - if can relay messages not subscribed
+ * @property {boolean} [emitSelf = false] - if publish should emit to self, if subscribed
  */
 
 /**
@@ -52,13 +60,7 @@ const {
  */
 class PubsubBaseProtocol extends EventEmitter {
   /**
-   * @param {Object} props
-   * @param {string} props.debugName - log namespace
-   * @param {Array<string>|string} props.multicodecs - protocol identificers to connect
-   * @param {Libp2p} props.libp2p
-   * @param {SignaturePolicyType} [props.globalSignaturePolicy = SignaturePolicy.StrictSign] - defines how signatures should be handled
-   * @param {boolean} [props.canRelayMessage = false] - if can relay messages not subscribed
-   * @param {boolean} [props.emitSelf = false] - if publish should emit to self, if subscribed
+   * @param {PubsubProperties & PubsubOptions} props
    * @abstract
    */
   constructor ({
@@ -83,8 +85,9 @@ class PubsubBaseProtocol extends EventEmitter {
 
     super()
 
-    this.log = debug(debugName)
-    this.log.err = debug(`${debugName}:error`)
+    this.log = Object.assign(debug(debugName), {
+      err: debug(`${debugName}:error`)
+    })
 
     /**
      * @type {Array<string>}
@@ -122,7 +125,7 @@ class PubsubBaseProtocol extends EventEmitter {
 
     // validate signature policy
     if (!SignaturePolicy[globalSignaturePolicy]) {
-      throw errcode(new Error('Invalid global signature policy'), codes.ERR_INVALID_SIGUATURE_POLICY)
+      throw errcode(new Error('Invalid global signature policy'), codes.ERR_INVALID_SIGNATURE_POLICY)
     }
 
     /**
@@ -379,7 +382,9 @@ class PubsubBaseProtocol extends EventEmitter {
 
     if (subs.length) {
       // update peer subscriptions
-      subs.forEach((subOpt) => this._processRpcSubOpt(idB58Str, subOpt))
+      subs.forEach((/** @type {RPCSubOpts} */ subOpt) => {
+        this._processRpcSubOpt(idB58Str, subOpt)
+      })
       this.emit('pubsub:subscription-change', peerStreams.id, subs)
     }
 
@@ -389,8 +394,9 @@ class PubsubBaseProtocol extends EventEmitter {
     }
 
     if (msgs.length) {
-      msgs.forEach(message => {
-        if (!(this.canRelayMessage || message.topicIDs.some((topic) => this.subscriptions.has(topic)))) {
+      // @ts-ignore RPC message is modified
+      msgs.forEach((message) => {
+        if (!(this.canRelayMessage || message.topicIDs.some((/** @type {string} */ topic) => this.subscriptions.has(topic)))) {
           this.log('received message we didn\'t subscribe to. Dropping.')
           return
         }
@@ -589,7 +595,7 @@ class PubsubBaseProtocol extends EventEmitter {
     for (const topic of message.topicIDs) {
       const validatorFn = this.topicValidators.get(topic)
       if (!validatorFn) {
-        continue
+        continue // eslint-disable-line 
       }
       await validatorFn(topic, message)
     }
diff --git a/src/pubsub/message/index.js b/src/pubsub/message/index.js
index c5e6329..2a30183 100644
--- a/src/pubsub/message/index.js
+++ b/src/pubsub/message/index.js
@@ -1,17 +1,16 @@
 'use strict'
 
+// @ts-ignore protons not typed
 const protons = require('protons')
 
 const rpcProto = protons(require('./rpc.proto.js'))
 const RPC = rpcProto.RPC
 const topicDescriptorProto = protons(require('./topic-descriptor.proto.js'))
 
-/**
- * @module pubsub/message/index
- */
-exports = module.exports
-exports.rpc = rpcProto
-exports.td = topicDescriptorProto
-exports.RPC = RPC
-exports.Message = RPC.Message
-exports.SubOpts = RPC.SubOpts
+module.exports = {
+  rpc: rpcProto,
+  td: topicDescriptorProto,
+  RPC,
+  Message: RPC.Message,
+  SubOpts: RPC.SubOpts
+}
diff --git a/src/pubsub/message/types.d.ts b/src/pubsub/message/types.d.ts
new file mode 100644
index 0000000..7e8c363
--- /dev/null
+++ b/src/pubsub/message/types.d.ts
@@ -0,0 +1,5 @@
+import { RPC, Message, SubOpts } from './types'
+
+export type RPC = RPC
+export type Message = Message
+export type SubOpts = SubOpts
diff --git a/src/pubsub/peer-streams.js b/src/pubsub/peer-streams.js
index 837870f..5a5886e 100644
--- a/src/pubsub/peer-streams.js
+++ b/src/pubsub/peer-streams.js
@@ -1,5 +1,10 @@
 'use strict'
 
+const debug = require('debug')
+const log = Object.assign(debug('libp2p-pubsub:peer-streams'), {
+  error: debug('libp2p-pubsub:peer-streams:err')
+})
+
 /** @typedef {import('../types').EventEmitterFactory} Events */
 /** @type Events */
 const EventEmitter = require('events')
@@ -10,10 +15,6 @@ const pushable = require('it-pushable')
 const { pipe } = require('it-pipe')
 const { source: abortable } = require('abortable-iterator')
 const AbortController = require('abort-controller').default
-const debug = require('debug')
-
-const log = debug('libp2p-pubsub:peer-streams')
-log.error = debug('libp2p-pubsub:peer-streams:error')
 
 /**
  * @typedef {import('../stream-muxer/types').MuxedStream} MuxedStream
@@ -168,7 +169,7 @@ class PeerStreams extends EventEmitter {
       this.outboundStream,
       lp.encode(),
       this._rawOutboundStream
-    ).catch(err => {
+    ).catch(/** @param {Error} err */ err => {
       log.error(err)
     })
 
diff --git a/src/pubsub/tests/api.js b/src/pubsub/tests/api.js
index 2de0cf7..e9a3147 100644
--- a/src/pubsub/tests/api.js
+++ b/src/pubsub/tests/api.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/pubsub/tests/emit-self.js b/src/pubsub/tests/emit-self.js
index a2a063e..a596e0e 100644
--- a/src/pubsub/tests/emit-self.js
+++ b/src/pubsub/tests/emit-self.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/pubsub/tests/index.js b/src/pubsub/tests/index.js
index 1b1414b..f089f5a 100644
--- a/src/pubsub/tests/index.js
+++ b/src/pubsub/tests/index.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/pubsub/tests/messages.js b/src/pubsub/tests/messages.js
index f827710..7c7ed44 100644
--- a/src/pubsub/tests/messages.js
+++ b/src/pubsub/tests/messages.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/pubsub/tests/multiple-nodes.js b/src/pubsub/tests/multiple-nodes.js
index 41cc9b4..0204c43 100644
--- a/src/pubsub/tests/multiple-nodes.js
+++ b/src/pubsub/tests/multiple-nodes.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 /* eslint max-nested-callbacks: ["error", 6] */
 'use strict'
diff --git a/src/pubsub/tests/two-nodes.js b/src/pubsub/tests/two-nodes.js
index 028e0aa..18b6b8d 100644
--- a/src/pubsub/tests/two-nodes.js
+++ b/src/pubsub/tests/two-nodes.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 /* eslint max-nested-callbacks: ["error", 6] */
 'use strict'
diff --git a/src/pubsub/tests/utils.js b/src/pubsub/tests/utils.js
index 7d16ac4..99b1c75 100644
--- a/src/pubsub/tests/utils.js
+++ b/src/pubsub/tests/utils.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 'use strict'
 
 const { expect } = require('chai')
diff --git a/src/pubsub/utils.js b/src/pubsub/utils.js
index 255ccf3..8dc0367 100644
--- a/src/pubsub/utils.js
+++ b/src/pubsub/utils.js
@@ -1,11 +1,11 @@
 'use strict'
 
+// @ts-ignore libp2p crypto has no types
 const randomBytes = require('libp2p-crypto/src/random-bytes')
 const uint8ArrayToString = require('uint8arrays/to-string')
 const uint8ArrayFromString = require('uint8arrays/from-string')
 const PeerId = require('peer-id')
 const multihash = require('multihashes')
-exports = module.exports
 
 /**
  * Generatea random sequence number.
@@ -13,7 +13,7 @@ exports = module.exports
  * @returns {Uint8Array}
  * @private
  */
-exports.randomSeqno = () => {
+const randomSeqno = () => {
   return randomBytes(8)
 }
 
@@ -25,7 +25,7 @@ exports.randomSeqno = () => {
  * @returns {Uint8Array}
  * @private
  */
-exports.msgId = (from, seqno) => {
+const msgId = (from, seqno) => {
   const fromBytes = PeerId.createFromB58String(from).id
   const msgId = new Uint8Array(fromBytes.length + seqno.length)
   msgId.set(fromBytes, 0)
@@ -40,22 +40,28 @@ exports.msgId = (from, seqno) => {
  * @returns {Uint8Array}
  * @private
  */
-exports.noSignMsgId = (data) => multihash.encode(data, 'sha2-256')
+const noSignMsgId = (data) => multihash.encode(data, 'sha2-256')
 
 /**
  * Check if any member of the first set is also a member
  * of the second set.
  *
- * @param {Set|Array} a
- * @param {Set|Array} b
+ * @param {Set<number>|Array<number>} a
+ * @param {Set<number>|Array<number>} b
  * @returns {boolean}
  * @private
  */
-exports.anyMatch = (a, b) => {
+const anyMatch = (a, b) => {
   let bHas
   if (Array.isArray(b)) {
+    /**
+     * @param {number} val
+     */
     bHas = (val) => b.indexOf(val) > -1
   } else {
+    /**
+     * @param {number} val
+     */
     bHas = (val) => b.has(val)
   }
 
@@ -76,7 +82,7 @@ exports.anyMatch = (a, b) => {
  * @returns {T[]}
  * @private
  */
-exports.ensureArray = (maybeArray) => {
+const ensureArray = (maybeArray) => {
   if (!Array.isArray(maybeArray)) {
     return [maybeArray]
   }
@@ -92,7 +98,7 @@ exports.ensureArray = (maybeArray) => {
  * @param {string} [peerId]
  * @returns {T & {from?: string, peerId?: string }}
  */
-exports.normalizeInRpcMessage = (message, peerId) => {
+const normalizeInRpcMessage = (message, peerId) => {
   const m = Object.assign({}, message)
   if (message.from instanceof Uint8Array) {
     m.from = uint8ArrayToString(message.from, 'base58btc')
@@ -109,7 +115,7 @@ exports.normalizeInRpcMessage = (message, peerId) => {
  * @param {T} message
  * @returns {T & {from?: Uint8Array, data?: Uint8Array}}
  */
-exports.normalizeOutRpcMessage = (message) => {
+const normalizeOutRpcMessage = (message) => {
   const m = Object.assign({}, message)
   if (typeof message.from === 'string') {
     m.from = uint8ArrayFromString(message.from, 'base58btc')
@@ -119,3 +125,13 @@ exports.normalizeOutRpcMessage = (message) => {
   }
   return m
 }
+
+module.exports = {
+  randomSeqno,
+  msgId,
+  noSignMsgId,
+  anyMatch,
+  ensureArray,
+  normalizeInRpcMessage,
+  normalizeOutRpcMessage
+}
diff --git a/src/record/tests/index.js b/src/record/tests/index.js
index 2879002..f15b5f9 100644
--- a/src/record/tests/index.js
+++ b/src/record/tests/index.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 
 'use strict'
diff --git a/src/record/types.ts b/src/record/types.d.ts
similarity index 100%
rename from src/record/types.ts
rename to src/record/types.d.ts
diff --git a/src/stream-muxer/tests/base-test.js b/src/stream-muxer/tests/base-test.js
index 064cf02..ce983f0 100644
--- a/src/stream-muxer/tests/base-test.js
+++ b/src/stream-muxer/tests/base-test.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/stream-muxer/tests/close-test.js b/src/stream-muxer/tests/close-test.js
index 2f212c4..e70dc56 100644
--- a/src/stream-muxer/tests/close-test.js
+++ b/src/stream-muxer/tests/close-test.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 /* eslint max-nested-callbacks: ["error", 8] */
 'use strict'
diff --git a/src/stream-muxer/tests/index.js b/src/stream-muxer/tests/index.js
index 9006539..d8c9cdc 100644
--- a/src/stream-muxer/tests/index.js
+++ b/src/stream-muxer/tests/index.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/stream-muxer/tests/mega-stress-test.js b/src/stream-muxer/tests/mega-stress-test.js
index b012ea1..c7b81ab 100644
--- a/src/stream-muxer/tests/mega-stress-test.js
+++ b/src/stream-muxer/tests/mega-stress-test.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/stream-muxer/tests/spawner.js b/src/stream-muxer/tests/spawner.js
index 2b2dc2e..b79ec06 100644
--- a/src/stream-muxer/tests/spawner.js
+++ b/src/stream-muxer/tests/spawner.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 'use strict'
 
 const { expect } = require('chai')
diff --git a/src/stream-muxer/tests/stress-test.js b/src/stream-muxer/tests/stress-test.js
index f32307b..9903122 100644
--- a/src/stream-muxer/tests/stress-test.js
+++ b/src/stream-muxer/tests/stress-test.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/stream-muxer/types.ts b/src/stream-muxer/types.d.ts
similarity index 89%
rename from src/stream-muxer/types.ts
rename to src/stream-muxer/types.d.ts
index 6d525a8..cf0c6f4 100644
--- a/src/stream-muxer/types.ts
+++ b/src/stream-muxer/types.d.ts
@@ -43,9 +43,9 @@ export interface MuxedStream extends AsyncIterable<Uint8Array | BufferList> {
   abort: () => void;
   reset: () => void;
   sink: Sink;
-  source: () => AsyncIterable<Uint8Array | BufferList>;
+  source: AsyncIterable<Uint8Array | BufferList>;
   timeline: MuxedTimeline;
   id: string;
 }
 
-export type Sink = (source: Uint8Array) => Promise<Uint8Array>;
+export type Sink = (source: Uint8Array) => Promise<void>;
diff --git a/src/topology/index.js b/src/topology/index.js
index e73b036..85e72db 100644
--- a/src/topology/index.js
+++ b/src/topology/index.js
@@ -62,6 +62,9 @@ class Topology {
     return Boolean(other && other[topologySymbol])
   }
 
+  /**
+   * @param {any} registrar
+   */
   set registrar (registrar) { // eslint-disable-line
     this._registrar = registrar
   }
diff --git a/src/topology/multicodec-topology.js b/src/topology/multicodec-topology.js
index 2b1cb9d..02e739e 100644
--- a/src/topology/multicodec-topology.js
+++ b/src/topology/multicodec-topology.js
@@ -56,6 +56,9 @@ class MulticodecTopology extends Topology {
     return Boolean(other && other[multicodecTopologySymbol])
   }
 
+  /**
+   * @param {any} registrar
+   */
   set registrar (registrar) { // eslint-disable-line
     this._registrar = registrar
     this._registrar.peerStore.on('change:protocols', this._onProtocolChange)
diff --git a/src/topology/tests/multicodec-topology.js b/src/topology/tests/multicodec-topology.js
index 747ad1a..0e824e2 100644
--- a/src/topology/tests/multicodec-topology.js
+++ b/src/topology/tests/multicodec-topology.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 
 'use strict'
diff --git a/src/topology/tests/topology.js b/src/topology/tests/topology.js
index 89f28d7..e551af6 100644
--- a/src/topology/tests/topology.js
+++ b/src/topology/tests/topology.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 
 'use strict'
diff --git a/src/transport/tests/dial-test.js b/src/transport/tests/dial-test.js
index 671365b..bfb01e5 100644
--- a/src/transport/tests/dial-test.js
+++ b/src/transport/tests/dial-test.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/transport/tests/filter-test.js b/src/transport/tests/filter-test.js
index 09c53a3..f4de22e 100644
--- a/src/transport/tests/filter-test.js
+++ b/src/transport/tests/filter-test.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/transport/tests/index.js b/src/transport/tests/index.js
index 0d43233..35b8272 100644
--- a/src/transport/tests/index.js
+++ b/src/transport/tests/index.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint-env mocha */
 'use strict'
 
diff --git a/src/transport/tests/listen-test.js b/src/transport/tests/listen-test.js
index cff92a7..5aaa030 100644
--- a/src/transport/tests/listen-test.js
+++ b/src/transport/tests/listen-test.js
@@ -1,3 +1,4 @@
+// @ts-nocheck interface tests
 /* eslint max-nested-callbacks: ["error", 8] */
 /* eslint-env mocha */
 'use strict'
diff --git a/src/transport/types.ts b/src/transport/types.d.ts
similarity index 95%
rename from src/transport/types.ts
rename to src/transport/types.d.ts
index af5df59..f1e19eb 100644
--- a/src/transport/types.ts
+++ b/src/transport/types.d.ts
@@ -1,3 +1,4 @@
+import BufferList from 'bl'
 import events from 'events'
 import Multiaddr from 'multiaddr'
 import Connection from '../connection/connection'
@@ -62,7 +63,7 @@ export type MultiaddrConnectionTimeline = {
 
 export type MultiaddrConnection = {
   sink: Sink;
-  source: () => AsyncIterable<Uint8Array>;
+  source: AsyncIterable<Uint8Array | BufferList>;
   close: (err?: Error) => Promise<void>;
   conn: unknown;
   remoteAddr: Multiaddr;
diff --git a/src/types.ts b/src/types.d.ts
similarity index 78%
rename from src/types.ts
rename to src/types.d.ts
index 554dfdf..2bfc046 100644
--- a/src/types.ts
+++ b/src/types.d.ts
@@ -3,13 +3,13 @@ export interface EventEmitterFactory {
 }
 
 export interface EventEmitter {
-  addListener(event: string | symbol, listener: (...args: any[]) => void);
-  on(event: string | symbol, listener: (...args: any[]) => void);
-  once(event: string | symbol, listener: (...args: any[]) => void);
-  removeListener(event: string | symbol, listener: (...args: any[]) => void);
-  off(event: string | symbol, listener: (...args: any[]) => void);
-  removeAllListeners(event?: string | symbol);
-  setMaxListeners(n: number);
+  addListener(event: string | symbol, listener: (...args: any[]) => void): EventEmitter;
+  on(event: string | symbol, listener: (...args: any[]) => void): EventEmitter;
+  once(event: string | symbol, listener: (...args: any[]) => void): EventEmitter;
+  removeListener(event: string | symbol, listener: (...args: any[]) => void): EventEmitter;
+  off(event: string | symbol, listener: (...args: any[]) => void): EventEmitter;
+  removeAllListeners(event?: string | symbol): EventEmitter;
+  setMaxListeners(n: number): EventEmitter;
   getMaxListeners(): number;
   listeners(event: string | symbol): Function[]; // eslint-disable-line @typescript-eslint/ban-types
   rawListeners(event: string | symbol): Function[]; // eslint-disable-line @typescript-eslint/ban-types