diff --git a/.eslintrc b/.eslintrc
index cea2e6c9..1254442e 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -5,6 +5,7 @@
     "@typescript-eslint/quotes": ["error", "double"],
     "require-await": "off",
     "@typescript-eslint/strict-boolean-expressions": "off",
+    "@typescript-eslint/no-extraneous-class": "off",
     "@typescript-eslint/no-explicit-any": "off",
     "no-await-in-loop": "off",
     "class-methods-use-this": "off"
diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 22b8a100..34b18a3b 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -175,7 +175,19 @@ jobs:
           timeout_minutes: 5
           max_attempts: 1
           command: |
-            pnpm run test
+            pnpm run clean.temp
+            pnpm run test.unit
+        continue-on-error: true
+
+      - name: Test Compatibility
+        if: ${{ !matrix.docker }}
+        uses: nick-fields/retry@v3
+        with:
+          timeout_minutes: 5
+          max_attempts: 1
+          command: |
+            pnpm run clean.temp
+            pnpm run test.unit.compat
         continue-on-error: true
 
       - name: Test Electron (Main)
diff --git a/.mocharc.js b/.mocharc.js
index 1411e927..3cc6d952 100644
--- a/.mocharc.js
+++ b/.mocharc.js
@@ -3,13 +3,14 @@
  */
 const config = {
   require: ["ts-node/register"],
-  spec: ["test/unit/*-test.ts", "test/unit/compat/*-test.js"],
   "expose-gc": true,
   "v8-expose-gc": true,
   exit: true,
   parallel: true,
-  timeout: 10000,
-  retries: 3,
+  timeout: 5000,
+  retries: 1,
+  fullTrace: true,
+  bail: false,
 }
 
 module.exports = config
diff --git a/.vscode/settings.json b/.vscode/settings.json
index 350f941b..c0a09f4b 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -13,10 +13,13 @@
   },
   "mochaExplorer.parallel": true,
   "mochaExplorer.globImplementation": "vscode",
-  "mochaExplorer.nodeArgv": [
-    "--expose-gc"
-  ],
+  "mochaExplorer.nodeArgv": ["--expose-gc"],
   "mochaExplorer.debuggerConfig": "JS-Attach",
+  "mochaExplorer.env": {
+    "INCLUDE_COMPAT_TESTS": "true"
+  },
+  "mochaExplorer.files": "test/unit/**/*-test.ts",
+  "mochaExplorer.mochaPath": "./node_modules/mocha",
   "files.exclude": {
     "**/.DS_Store": true,
     "**/Thumbs.db": true,
diff --git a/package.json b/package.json
index f1f2c06f..c4975a9d 100644
--- a/package.json
+++ b/package.json
@@ -36,6 +36,7 @@
     "@types/which": "^3.0.4",
     "benchmark": "^2.1.4",
     "chai": "^4",
+    "cross-env": "^7.0.3",
     "deasync": "^0.1.30",
     "downlevel-dts": "^0.11.0",
     "electron-mocha": "^13.0.0",
@@ -97,9 +98,11 @@
     "build.native.debug": "cmake-ts dev-os-only",
     "build": "run-p build.js build.native",
     "build.debug": "run-s build.js build.native.debug",
-    "test": "run-s clean.temp build && mocha",
+    "test": "run-s test.unit",
+    "test.unit": "run-s clean.temp build && cross-env INCLUDE_COMPAT_TESTS=false mocha ./test/unit/*-test.ts",
+    "test.unit.compat": "run-s clean.temp build && cross-env INCLUDE_COMPAT_TESTS=true mocha ./test/unit/compat/*-test.ts",
     "test.smoke": "bash ./script/smoke-test.bash",
-    "test.skip_gc_tests": "run-s clean.temp build.debug && cross-env SKIP_GC_TESTS=true mocha",
+    "test.skip_gc_tests": "run-s clean.temp build && cross-env SKIP_GC_TESTS=true mocha",
     "test.electron.main": "run-s clean.temp build && electron-mocha",
     "format": "run-s format.prettier format.clang-format",
     "format.prettier": "prettier -l --cache --cache-location ./.cache/prettier --write .",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 9246484d..de10f953 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -58,6 +58,9 @@ importers:
       chai:
         specifier: ^4
         version: 4.5.0
+      cross-env:
+        specifier: ^7.0.3
+        version: 7.0.3
       deasync:
         specifier: ^0.1.30
         version: 0.1.30
@@ -953,6 +956,11 @@ packages:
   create-require@1.1.1:
     resolution: {integrity: sha512-dcKFX3jn0MpIaXjisoRvexIJVEKzaq7z2rZKxf+MSr9TkdmHmsU4m2lcLojrj/FHl8mk5VxMmYA+ftRkP/3oKQ==}
 
+  cross-env@7.0.3:
+    resolution: {integrity: sha512-+/HKd6EgcQCJGh2PSjZuUitQBQynKor4wrFbRg4DtAgS1aWO+gU52xpH7M9ScGgXSYmAVS9bIJ8EzuaGw0oNAw==}
+    engines: {node: '>=10.14', npm: '>=6', yarn: '>=1'}
+    hasBin: true
+
   cross-spawn@7.0.3:
     resolution: {integrity: sha512-iRDPJKUPVEND7dHPO8rkbOnPpyDygcDFtWjpeWNCgy8WP2rXcxXL8TskReQl6OrB2G7+UJrags1q15Fudc7G6w==}
     engines: {node: '>= 8'}
@@ -4462,6 +4470,10 @@ snapshots:
 
   create-require@1.1.1: {}
 
+  cross-env@7.0.3:
+    dependencies:
+      cross-spawn: 7.0.3
+
   cross-spawn@7.0.3:
     dependencies:
       path-key: 3.1.1
diff --git a/src/compat.ts b/src/compat.ts
index 59174423..7314439d 100644
--- a/src/compat.ts
+++ b/src/compat.ts
@@ -6,6 +6,9 @@
 import {EventEmitter} from "events"
 import * as zmq from "."
 import {FullError} from "./errors"
+import * as longOptions from "./compat/long-options"
+import * as pollStates from "./compat/poll-states"
+import * as sendOptions from "./compat/send-options"
 
 type AnySocket =
   | zmq.Pair
@@ -22,99 +25,6 @@ type AnySocket =
   | zmq.Stream
 
 let count = 1
-const types = {
-  ZMQ_PAIR: 0,
-  ZMQ_PUB: 1,
-  ZMQ_SUB: 2,
-  ZMQ_REQ: 3,
-  ZMQ_REP: 4,
-  ZMQ_DEALER: 5,
-  ZMQ_XREQ: 5,
-  ZMQ_ROUTER: 6,
-  ZMQ_XREP: 6,
-  ZMQ_PULL: 7,
-  ZMQ_PUSH: 8,
-  ZMQ_XPUB: 9,
-  ZMQ_XSUB: 10,
-  ZMQ_STREAM: 11,
-}
-
-const longOptions = {
-  ZMQ_AFFINITY: 4,
-  ZMQ_IDENTITY: 5,
-  ZMQ_SUBSCRIBE: 6,
-  ZMQ_UNSUBSCRIBE: 7,
-  ZMQ_RATE: 8,
-  ZMQ_RECOVERY_IVL: 9,
-  ZMQ_RECOVERY_IVL_MSEC: 9,
-  ZMQ_SNDBUF: 11,
-  ZMQ_RCVBUF: 12,
-  ZMQ_RCVMORE: 13,
-  ZMQ_FD: 14,
-  ZMQ_EVENTS: 15,
-  ZMQ_TYPE: 16,
-  ZMQ_LINGER: 17,
-  ZMQ_RECONNECT_IVL: 18,
-  ZMQ_BACKLOG: 19,
-  ZMQ_RECONNECT_IVL_MAX: 21,
-  ZMQ_MAXMSGSIZE: 22,
-  ZMQ_SNDHWM: 23,
-  ZMQ_RCVHWM: 24,
-  ZMQ_MULTICAST_HOPS: 25,
-  ZMQ_RCVTIMEO: 27,
-  ZMQ_SNDTIMEO: 28,
-  ZMQ_IPV4ONLY: 31,
-  ZMQ_LAST_ENDPOINT: 32,
-  ZMQ_ROUTER_MANDATORY: 33,
-  ZMQ_TCP_KEEPALIVE: 34,
-  ZMQ_TCP_KEEPALIVE_CNT: 35,
-  ZMQ_TCP_KEEPALIVE_IDLE: 36,
-  ZMQ_TCP_KEEPALIVE_INTVL: 37,
-  ZMQ_TCP_ACCEPT_FILTER: 38,
-  ZMQ_DELAY_ATTACH_ON_CONNECT: 39,
-  ZMQ_XPUB_VERBOSE: 40,
-  ZMQ_ROUTER_RAW: 41,
-  ZMQ_IPV6: 42,
-  ZMQ_MECHANISM: 43,
-  ZMQ_PLAIN_SERVER: 44,
-  ZMQ_PLAIN_USERNAME: 45,
-  ZMQ_PLAIN_PASSWORD: 46,
-  ZMQ_CURVE_SERVER: 47,
-  ZMQ_CURVE_PUBLICKEY: 48,
-  ZMQ_CURVE_SECRETKEY: 49,
-  ZMQ_CURVE_SERVERKEY: 50,
-  ZMQ_ZAP_DOMAIN: 55,
-  ZMQ_HEARTBEAT_IVL: 75,
-  ZMQ_HEARTBEAT_TTL: 76,
-  ZMQ_HEARTBEAT_TIMEOUT: 77,
-  ZMQ_CONNECT_TIMEOUT: 79,
-  ZMQ_IO_THREADS: 1,
-  ZMQ_MAX_SOCKETS: 2,
-  ZMQ_ROUTER_HANDOVER: 56,
-}
-
-const pollStates = {
-  ZMQ_POLLIN: 1,
-  ZMQ_POLLOUT: 2,
-  ZMQ_POLLERR: 4,
-}
-
-const sendOptions = {
-  ZMQ_SNDMORE: 2,
-}
-
-const capabilities = {
-  ZMQ_CAN_MONITOR: 1,
-  ZMQ_CAN_DISCONNECT: 1,
-  ZMQ_CAN_UNBIND: 1,
-  ZMQ_CAN_SET_CTX: 1,
-}
-
-const socketStates = {
-  STATE_READY: 0,
-  STATE_BUSY: 1,
-  STATE_CLOSED: 2,
-}
 
 const shortOptions = {
   _fd: longOptions.ZMQ_FD,
@@ -241,9 +151,11 @@ class Socket extends EventEmitter {
       case "stream":
         this._socket = new zmq.Stream()
         break
+      default:
+        throw new Error(`Invalid socket type: ${type}`)
     }
 
-    const recv = async () => {
+    const recv = () => {
       this.once("_flushRecv", async () => {
         while (!this._socket.closed && !this._paused) {
           await this._recv()
@@ -347,7 +259,7 @@ class Socket extends EventEmitter {
       .catch(err => {
         process.nextTick(() => {
           if (cb) {
-            cb(err)
+            cb(err as Error)
           } else {
             this.emit("error", err)
           }
@@ -371,7 +283,7 @@ class Socket extends EventEmitter {
       .catch(err => {
         process.nextTick(() => {
           if (cb) {
-            cb(err)
+            cb(err as Error)
           } else {
             this.emit("error", err)
           }
@@ -391,8 +303,12 @@ class Socket extends EventEmitter {
     return this
   }
 
-  send(message: zmq.MessageLike[], flags = 0, cb?: Callback) {
-    flags = flags | 0
+  send(
+    message: zmq.MessageLike[] | zmq.MessageLike,
+    givenFlags: number | undefined | null = 0,
+    cb: Callback | undefined = undefined,
+  ) {
+    const flags = (givenFlags ?? 0) | 0
     this._msg = this._msg.concat(message)
     if ((flags & sendOptions.ZMQ_SNDMORE) === 0) {
       this._sendQueue.push([this._msg, cb])
@@ -460,7 +376,7 @@ class Socket extends EventEmitter {
     return this._socket.closed
   }
 
-  monitor(interval: number, num: number) {
+  monitor(interval?: number, num?: number) {
     this._count = count++
 
     /* eslint-disable-next-line no-unused-expressions */
@@ -560,8 +476,9 @@ class Socket extends EventEmitter {
     }
   }
 
-  setsockopt(option: number | keyof typeof shortOptions, value: any) {
-    option = typeof option !== "number" ? shortOptions[option] : option
+  setsockopt(givenOption: number | keyof typeof shortOptions, value: any) {
+    const option =
+      typeof givenOption === "number" ? givenOption : shortOptions[givenOption]
 
     switch (option) {
       case longOptions.ZMQ_AFFINITY:
@@ -699,8 +616,9 @@ class Socket extends EventEmitter {
     return this
   }
 
-  getsockopt(option: number | keyof typeof shortOptions) {
-    option = typeof option !== "number" ? shortOptions[option] : option
+  getsockopt(givenOption: number | keyof typeof shortOptions) {
+    const option =
+      typeof givenOption !== "number" ? shortOptions[givenOption] : givenOption
 
     switch (option) {
       case longOptions.ZMQ_AFFINITY:
@@ -822,10 +740,9 @@ for (const key in shortOptions) {
     get(this: Socket) {
       return this.getsockopt(shortOptions[key as keyof typeof shortOptions])
     },
-    set(this: Socket, val: string | Buffer) {
-      if ("string" === typeof val) {
-        val = Buffer.from(val, "utf8")
-      }
+    set(this: Socket, givenVal: string | Buffer) {
+      const val =
+        typeof givenVal === "string" ? Buffer.from(givenVal, "utf8") : givenVal
       return this.setsockopt(
         shortOptions[key as keyof typeof shortOptions],
         val,
@@ -909,11 +826,9 @@ export {
   shortOptions as options,
 }
 
-/* Unfortunately there is no easy way to include these in the resulting
-   TS definitions. */
-Object.assign(module.exports, longOptions)
-Object.assign(module.exports, types)
-Object.assign(module.exports, pollStates)
-Object.assign(module.exports, sendOptions)
-Object.assign(module.exports, socketStates)
-Object.assign(module.exports, capabilities)
+export * from "./compat/long-options"
+export * from "./compat/types"
+export * from "./compat/poll-states"
+export * from "./compat/send-options"
+export * from "./compat/capabilities"
+export * from "./compat/socket-states"
diff --git a/src/compat/capabilities.ts b/src/compat/capabilities.ts
new file mode 100644
index 00000000..a7b8a4e0
--- /dev/null
+++ b/src/compat/capabilities.ts
@@ -0,0 +1,4 @@
+export const ZMQ_CAN_MONITOR = 1
+export const ZMQ_CAN_DISCONNECT = 1
+export const ZMQ_CAN_UNBIND = 1
+export const ZMQ_CAN_SET_CTX = 1
diff --git a/src/compat/long-options.ts b/src/compat/long-options.ts
new file mode 100644
index 00000000..80d74404
--- /dev/null
+++ b/src/compat/long-options.ts
@@ -0,0 +1,51 @@
+export const ZMQ_AFFINITY = 4
+export const ZMQ_IDENTITY = 5
+export const ZMQ_SUBSCRIBE = 6
+export const ZMQ_UNSUBSCRIBE = 7
+export const ZMQ_RATE = 8
+export const ZMQ_RECOVERY_IVL = 9
+export const ZMQ_RECOVERY_IVL_MSEC = 9
+export const ZMQ_SNDBUF = 11
+export const ZMQ_RCVBUF = 12
+export const ZMQ_RCVMORE = 13
+export const ZMQ_FD = 14
+export const ZMQ_EVENTS = 15
+export const ZMQ_TYPE = 16
+export const ZMQ_LINGER = 17
+export const ZMQ_RECONNECT_IVL = 18
+export const ZMQ_BACKLOG = 19
+export const ZMQ_RECONNECT_IVL_MAX = 21
+export const ZMQ_MAXMSGSIZE = 22
+export const ZMQ_SNDHWM = 23
+export const ZMQ_RCVHWM = 24
+export const ZMQ_MULTICAST_HOPS = 25
+export const ZMQ_RCVTIMEO = 27
+export const ZMQ_SNDTIMEO = 28
+export const ZMQ_IPV4ONLY = 31
+export const ZMQ_LAST_ENDPOINT = 32
+export const ZMQ_ROUTER_MANDATORY = 33
+export const ZMQ_TCP_KEEPALIVE = 34
+export const ZMQ_TCP_KEEPALIVE_CNT = 35
+export const ZMQ_TCP_KEEPALIVE_IDLE = 36
+export const ZMQ_TCP_KEEPALIVE_INTVL = 37
+export const ZMQ_TCP_ACCEPT_FILTER = 38
+export const ZMQ_DELAY_ATTACH_ON_CONNECT = 39
+export const ZMQ_XPUB_VERBOSE = 40
+export const ZMQ_ROUTER_RAW = 41
+export const ZMQ_IPV6 = 42
+export const ZMQ_MECHANISM = 43
+export const ZMQ_PLAIN_SERVER = 44
+export const ZMQ_PLAIN_USERNAME = 45
+export const ZMQ_PLAIN_PASSWORD = 46
+export const ZMQ_CURVE_SERVER = 47
+export const ZMQ_CURVE_PUBLICKEY = 48
+export const ZMQ_CURVE_SECRETKEY = 49
+export const ZMQ_CURVE_SERVERKEY = 50
+export const ZMQ_ZAP_DOMAIN = 55
+export const ZMQ_HEARTBEAT_IVL = 75
+export const ZMQ_HEARTBEAT_TTL = 76
+export const ZMQ_HEARTBEAT_TIMEOUT = 77
+export const ZMQ_CONNECT_TIMEOUT = 79
+export const ZMQ_IO_THREADS = 1
+export const ZMQ_MAX_SOCKETS = 2
+export const ZMQ_ROUTER_HANDOVER = 56
diff --git a/src/compat/poll-states.ts b/src/compat/poll-states.ts
new file mode 100644
index 00000000..47bae768
--- /dev/null
+++ b/src/compat/poll-states.ts
@@ -0,0 +1,3 @@
+export const ZMQ_POLLIN = 1
+export const ZMQ_POLLOUT = 2
+export const ZMQ_POLLERR = 4
diff --git a/src/compat/send-options.ts b/src/compat/send-options.ts
new file mode 100644
index 00000000..e826e8b1
--- /dev/null
+++ b/src/compat/send-options.ts
@@ -0,0 +1 @@
+export const ZMQ_SNDMORE = 2
diff --git a/src/compat/socket-states.ts b/src/compat/socket-states.ts
new file mode 100644
index 00000000..c24a8e31
--- /dev/null
+++ b/src/compat/socket-states.ts
@@ -0,0 +1,3 @@
+export const STATE_READY = 0
+export const STATE_BUSY = 1
+export const STATE_CLOSED = 2
diff --git a/src/compat/types.ts b/src/compat/types.ts
new file mode 100644
index 00000000..80a51d07
--- /dev/null
+++ b/src/compat/types.ts
@@ -0,0 +1,14 @@
+export const ZMQ_PAIR = 0
+export const ZMQ_PUB = 1
+export const ZMQ_SUB = 2
+export const ZMQ_REQ = 3
+export const ZMQ_REP = 4
+export const ZMQ_DEALER = 5
+export const ZMQ_XREQ = 5
+export const ZMQ_ROUTER = 6
+export const ZMQ_XREP = 6
+export const ZMQ_PULL = 7
+export const ZMQ_PUSH = 8
+export const ZMQ_XPUB = 9
+export const ZMQ_XSUB = 10
+export const ZMQ_STREAM = 11
diff --git a/src/index.ts b/src/index.ts
index 5a2c219d..548f7a41 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -45,6 +45,7 @@ export type MessageLike =
   | ArrayBuffer /* Backing buffer of TypedArrays. */
   | SharedArrayBuffer
   | string
+  | number
   | null
 
 /**
diff --git a/test/tsconfig.json b/test/tsconfig.json
index b5bce5fa..d9a119c0 100644
--- a/test/tsconfig.json
+++ b/test/tsconfig.json
@@ -1,12 +1,8 @@
 {
   "extends": "../tsconfig.json",
-  "include": ["**/*.ts"],
+  "include": ["./unit/**/*.ts", "./*.ts"],
   "compilerOptions": {
-    "skipLibCheck": true,
-    "lib": [
-      "ES2020",
-      // only used in tests
-      "ES2021.WeakRef"
-    ]
-  }
+    "skipLibCheck": true
+  },
+  "compileOnSave": false
 }
diff --git a/test/unit/compat/README.md b/test/unit/compat/README.md
index 79babeb9..0b71a6c7 100644
--- a/test/unit/compat/README.md
+++ b/test/unit/compat/README.md
@@ -1,5 +1,6 @@
-The tests in this directory have been copied from the original ZeroMQ.js version
-(up to 5.x) for which the license and copyright notice is reproduced below.
+The tests in this directory have been modified from the original ZeroMQ.js
+version (up to 5.x) for which the license and copyright notice is reproduced
+below.
 
 Copyright (c) 2011 TJ Holowaychuk Copyright (c) 2010, 2011 Justin Tulloss
 
diff --git a/test/unit/compat/context-test.js b/test/unit/compat/context-test.ts
similarity index 80%
rename from test/unit/compat/context-test.js
rename to test/unit/compat/context-test.ts
index 741e5320..a460deb6 100644
--- a/test/unit/compat/context-test.js
+++ b/test/unit/compat/context-test.ts
@@ -1,7 +1,7 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   describe("compat context", function () {
     it("should support setting max io threads", function () {
       zmq.Context.setMaxThreads(3)
diff --git a/test/unit/compat/exports-test.js b/test/unit/compat/exports-test.js
deleted file mode 100644
index ff2eefe6..00000000
--- a/test/unit/compat/exports-test.js
+++ /dev/null
@@ -1,101 +0,0 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const semver = require("semver")
-  const {assert} = require("chai")
-
-  describe("compat exports", function () {
-    it("should export a valid version", function () {
-      assert.ok(semver.valid(zmq.version))
-    })
-
-    it("should generate valid curve keypair", function () {
-      if (!zmq.capability.curve) {
-        this.skip()
-      }
-
-      const curve = zmq.curveKeypair()
-      assert.typeOf(curve.public, "string")
-      assert.typeOf(curve.secret, "string")
-      assert.equal(curve.public.length, 40)
-      assert.equal(curve.secret.length, 40)
-    })
-
-    it("should export socket types and options", function () {
-      const constants = [
-        "PUB",
-        "SUB",
-        "REQ",
-        "XREQ",
-        "REP",
-        "XREP",
-        "DEALER",
-        "ROUTER",
-        "PUSH",
-        "PULL",
-        "PAIR",
-        "AFFINITY",
-        "IDENTITY",
-        "SUBSCRIBE",
-        "UNSUBSCRIBE",
-        "RCVTIMEO",
-        "SNDTIMEO",
-        "RATE",
-        "RECOVERY_IVL",
-        "SNDBUF",
-        "RCVBUF",
-        "RCVMORE",
-        "FD",
-        "EVENTS",
-        "TYPE",
-        "LINGER",
-        "RECONNECT_IVL",
-        "RECONNECT_IVL_MAX",
-        "BACKLOG",
-        "POLLIN",
-        "POLLOUT",
-        "POLLERR",
-        "SNDMORE",
-        "XPUB",
-        "XSUB",
-        "SNDHWM",
-        "RCVHWM",
-        "MAXMSGSIZE",
-        "MULTICAST_HOPS",
-        "TCP_KEEPALIVE",
-        "TCP_KEEPALIVE_CNT",
-        "TCP_KEEPALIVE_IDLE",
-        "TCP_KEEPALIVE_INTVL",
-        "IPV4ONLY",
-        "DELAY_ATTACH_ON_CONNECT",
-        "ROUTER_MANDATORY",
-        "XPUB_VERBOSE",
-        "TCP_KEEPALIVE",
-        "TCP_KEEPALIVE_IDLE",
-        "TCP_KEEPALIVE_CNT",
-        "TCP_KEEPALIVE_INTVL",
-        "TCP_ACCEPT_FILTER",
-        "LAST_ENDPOINT",
-        "ROUTER_RAW",
-      ]
-
-      constants.forEach(function (typeOrProp) {
-        assert.typeOf(zmq[`ZMQ_${typeOrProp}`], "number")
-      })
-    })
-
-    it("should export states", function () {
-      ;["STATE_READY", "STATE_BUSY", "STATE_CLOSED"].forEach(function (state) {
-        assert.typeOf(zmq[state], "number")
-      })
-    })
-
-    it("should export constructors", function () {
-      assert.typeOf(zmq.Context, "function")
-      assert.typeOf(zmq.Socket, "function")
-    })
-
-    it("should export methods", function () {
-      assert.typeOf(zmq.socket, "function")
-    })
-  })
-}
diff --git a/test/unit/compat/exports-test.ts b/test/unit/compat/exports-test.ts
new file mode 100644
index 00000000..893314a1
--- /dev/null
+++ b/test/unit/compat/exports-test.ts
@@ -0,0 +1,92 @@
+import * as zmq from "../../../v5-compat"
+import {capability} from "../../../src"
+import {assert} from "chai"
+import semver from "semver"
+
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
+  describe("compat exports", function () {
+    it("should export a valid version", function () {
+      assert.ok(semver.valid(zmq.version))
+    })
+
+    it("should generate valid curve keypair", function () {
+      if (!capability.curve) {
+        this.skip()
+      }
+
+      const curve = zmq.curveKeypair()
+      assert.typeOf(curve.public, "string")
+      assert.typeOf(curve.secret, "string")
+      assert.equal(curve.public.length, 40)
+      assert.equal(curve.secret.length, 40)
+    })
+
+    it("should export socket types and options", function () {
+      assert.typeOf(zmq.ZMQ_PUB, "number")
+      assert.typeOf(zmq.ZMQ_SUB, "number")
+      assert.typeOf(zmq.ZMQ_REQ, "number")
+      assert.typeOf(zmq.ZMQ_XREQ, "number")
+      assert.typeOf(zmq.ZMQ_REP, "number")
+      assert.typeOf(zmq.ZMQ_XREP, "number")
+      assert.typeOf(zmq.ZMQ_DEALER, "number")
+      assert.typeOf(zmq.ZMQ_ROUTER, "number")
+      assert.typeOf(zmq.ZMQ_PUSH, "number")
+      assert.typeOf(zmq.ZMQ_PULL, "number")
+      assert.typeOf(zmq.ZMQ_PAIR, "number")
+      assert.typeOf(zmq.ZMQ_AFFINITY, "number")
+      assert.typeOf(zmq.ZMQ_IDENTITY, "number")
+      assert.typeOf(zmq.ZMQ_SUBSCRIBE, "number")
+      assert.typeOf(zmq.ZMQ_UNSUBSCRIBE, "number")
+      assert.typeOf(zmq.ZMQ_RCVTIMEO, "number")
+      assert.typeOf(zmq.ZMQ_SNDTIMEO, "number")
+      assert.typeOf(zmq.ZMQ_RATE, "number")
+      assert.typeOf(zmq.ZMQ_RECOVERY_IVL, "number")
+      assert.typeOf(zmq.ZMQ_SNDBUF, "number")
+      assert.typeOf(zmq.ZMQ_RCVBUF, "number")
+      assert.typeOf(zmq.ZMQ_RCVMORE, "number")
+      assert.typeOf(zmq.ZMQ_FD, "number")
+      assert.typeOf(zmq.ZMQ_EVENTS, "number")
+      assert.typeOf(zmq.ZMQ_TYPE, "number")
+      assert.typeOf(zmq.ZMQ_LINGER, "number")
+      assert.typeOf(zmq.ZMQ_RECONNECT_IVL, "number")
+      assert.typeOf(zmq.ZMQ_RECONNECT_IVL_MAX, "number")
+      assert.typeOf(zmq.ZMQ_BACKLOG, "number")
+      assert.typeOf(zmq.ZMQ_POLLIN, "number")
+      assert.typeOf(zmq.ZMQ_POLLOUT, "number")
+      assert.typeOf(zmq.ZMQ_POLLERR, "number")
+      assert.typeOf(zmq.ZMQ_SNDMORE, "number")
+      assert.typeOf(zmq.ZMQ_XPUB, "number")
+      assert.typeOf(zmq.ZMQ_XSUB, "number")
+      assert.typeOf(zmq.ZMQ_SNDHWM, "number")
+      assert.typeOf(zmq.ZMQ_RCVHWM, "number")
+      assert.typeOf(zmq.ZMQ_MAXMSGSIZE, "number")
+      assert.typeOf(zmq.ZMQ_MULTICAST_HOPS, "number")
+      assert.typeOf(zmq.ZMQ_TCP_KEEPALIVE, "number")
+      assert.typeOf(zmq.ZMQ_TCP_KEEPALIVE_CNT, "number")
+      assert.typeOf(zmq.ZMQ_TCP_KEEPALIVE_IDLE, "number")
+      assert.typeOf(zmq.ZMQ_TCP_KEEPALIVE_INTVL, "number")
+      assert.typeOf(zmq.ZMQ_IPV4ONLY, "number")
+      assert.typeOf(zmq.ZMQ_DELAY_ATTACH_ON_CONNECT, "number")
+      assert.typeOf(zmq.ZMQ_ROUTER_MANDATORY, "number")
+      assert.typeOf(zmq.ZMQ_XPUB_VERBOSE, "number")
+      assert.typeOf(zmq.ZMQ_TCP_ACCEPT_FILTER, "number")
+      assert.typeOf(zmq.ZMQ_LAST_ENDPOINT, "number")
+      assert.typeOf(zmq.ZMQ_ROUTER_RAW, "number")
+    })
+
+    it("should export states", function () {
+      assert.typeOf(zmq.STATE_READY, "number")
+      assert.typeOf(zmq.STATE_BUSY, "number")
+      assert.typeOf(zmq.STATE_CLOSED, "number")
+    })
+
+    it("should export constructors", function () {
+      assert.typeOf(zmq.Context, "function")
+      assert.typeOf(zmq.Socket, "function")
+    })
+
+    it("should export methods", function () {
+      assert.typeOf(zmq.socket, "function")
+    })
+  })
+}
diff --git a/test/unit/compat/gc-test.js b/test/unit/compat/gc-test.ts
similarity index 83%
rename from test/unit/compat/gc-test.js
rename to test/unit/compat/gc-test.ts
index a742b630..54fbe41b 100644
--- a/test/unit/compat/gc-test.js
+++ b/test/unit/compat/gc-test.ts
@@ -1,10 +1,15 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   for (const proto of testProtos("tcp", "inproc")) {
     describe(`compat socket with ${proto}`, function () {
+      let address: string
+      beforeEach(async () => {
+        address = await uniqAddress(proto)
+      })
+
       it("should cooperate with gc", function (done) {
         const sockA = zmq.socket("dealer")
         const sockB = zmq.socket("dealer")
@@ -28,7 +33,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
 
         let bound = false
 
-        const address = uniqAddress(proto)
         sockA.bind(address, err => {
           if (err) {
             clearInterval(interval)
diff --git a/test/unit/compat/load.js b/test/unit/compat/load.js
deleted file mode 100644
index 64c26e6d..00000000
--- a/test/unit/compat/load.js
+++ /dev/null
@@ -1,10 +0,0 @@
-const path = require("path")
-
-module.exports = require(
-  process.env.ZMQ_COMPAT_PATH
-    ? path.resolve(process.cwd(), process.env.ZMQ_COMPAT_PATH)
-    : "../../../src/compat",
-)
-
-/* Copy capabilities from regular module. */
-module.exports.capability = require("../../../src").capability
diff --git a/test/unit/compat/socket-error-callback-test.js b/test/unit/compat/socket-error-callback-test.ts
similarity index 66%
rename from test/unit/compat/socket-error-callback-test.js
rename to test/unit/compat/socket-error-callback-test.ts
index d3c95fd0..4ced29c2 100644
--- a/test/unit/compat/socket-error-callback-test.js
+++ b/test/unit/compat/socket-error-callback-test.ts
@@ -1,9 +1,11 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
+import * as zmq from "../../../v5-compat"
+import type {Socket} from "../../../v5-compat"
+import {isFullError} from "../../../src/errors"
+import {assert} from "chai"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   describe("compat socket error callback", function () {
-    let sock
+    let sock: Socket
 
     beforeEach(function () {
       sock = zmq.socket("router")
@@ -20,9 +22,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
 
     it("should callback with error when not connected", function (done) {
       sock.send(["foo", "bar"], null, err => {
-        if (!isFullError(err)) {
-          throw err
-        }
+        assert.isUndefined(err)
         sock.close()
         done()
       })
diff --git a/test/unit/compat/socket-events-test.js b/test/unit/compat/socket-events-test.ts
similarity index 75%
rename from test/unit/compat/socket-events-test.js
rename to test/unit/compat/socket-events-test.ts
index edae1e85..0e0bd8e0 100644
--- a/test/unit/compat/socket-events-test.js
+++ b/test/unit/compat/socket-events-test.ts
@@ -1,16 +1,19 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   for (const proto of testProtos("tcp", "inproc")) {
     describe(`compat socket with ${proto} events`, function () {
+      let address: string
+      beforeEach(async () => {
+        address = await uniqAddress(proto)
+      })
+
       it("should support events", function (done) {
         const rep = zmq.socket("rep")
         const req = zmq.socket("req")
 
-        const address = uniqAddress(proto)
-
         rep.on("message", function (msg) {
           assert.instanceOf(msg, Buffer)
           assert.equal(msg.toString(), "hello")
diff --git a/test/unit/compat/socket-messages-test.js b/test/unit/compat/socket-messages-test.ts
similarity index 87%
rename from test/unit/compat/socket-messages-test.js
rename to test/unit/compat/socket-messages-test.ts
index 996069f8..c5173da1 100644
--- a/test/unit/compat/socket-messages-test.js
+++ b/test/unit/compat/socket-messages-test.ts
@@ -1,21 +1,21 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
-  for (const proto of testProtos("tcp", "inproc")) {
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
+  for (const proto of testProtos( "inproc")) {
     describe(`compat socket with ${proto} messages`, function () {
-      let push
-      let pull
+      let push: zmq.Socket
+      let pull: zmq.Socket
+      let address: string
 
-      beforeEach(function () {
+      beforeEach(async function () {
         push = zmq.socket("push")
         pull = zmq.socket("pull")
+        address = await uniqAddress(proto)
       })
 
       it("should support messages", function (done) {
-        const address = uniqAddress(proto)
-
         let n = 0
 
         pull.on("message", function (msg) {
@@ -44,8 +44,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       })
 
       it("should support multipart messages", function (done) {
-        const address = uniqAddress(proto)
-
         pull.on("message", function (msg1, msg2, msg3) {
           assert.equal(msg1.toString(), "string")
           assert.equal(msg2.toString(), "15.99")
@@ -61,8 +59,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       })
 
       it("should support sndmore", function (done) {
-        const address = uniqAddress(proto)
-
         pull.on("message", function (a, b, c, d, e) {
           assert.equal(a.toString(), "tobi")
           assert.equal(b.toString(), "loki")
@@ -83,7 +79,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
 
       if (proto != "inproc") {
         it("should handle late connect", function (done) {
-          const address = uniqAddress(proto)
           let n = 0
 
           pull.on("message", function (msg) {
@@ -116,7 +111,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       }
 
       it("should call send callbacks", function (done) {
-        const address = uniqAddress(proto)
         let received = 0
         let callbacks = 0
 
diff --git a/test/unit/compat/socket-monitor-test.js b/test/unit/compat/socket-monitor-test.ts
similarity index 86%
rename from test/unit/compat/socket-monitor-test.js
rename to test/unit/compat/socket-monitor-test.ts
index 4df0e03d..19971f7e 100644
--- a/test/unit/compat/socket-monitor-test.js
+++ b/test/unit/compat/socket-monitor-test.ts
@@ -1,13 +1,18 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const semver = require("semver")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
-  const {isFullError} = require("../../src/errors")
+import * as zmq from "../../../v5-compat"
+import semver from "semver"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
+import {isFullError} from "../../../src/errors"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   /* This test case only seems to work reliably with TCP. */
   for (const proto of testProtos("tcp")) {
     describe(`compat socket with ${proto} monitor`, function () {
+      let address: string
+      beforeEach(async () => {
+        address = await uniqAddress(proto)
+      })
+
       beforeEach(function () {
         /* ZMQ < 4.2 occasionally fails with assertion errors. */
         if (semver.satisfies(zmq.version, "< 4.2")) {
@@ -28,8 +33,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         const rep = zmq.socket("rep")
         const req = zmq.socket("req")
 
-        const address = uniqAddress(proto)
-
         rep.on("message", function (msg) {
           assert.instanceOf(msg, Buffer)
           assert.equal(msg.toString(), "hello")
diff --git a/test/unit/compat/socket-pair-test.js b/test/unit/compat/socket-pair-test.ts
similarity index 82%
rename from test/unit/compat/socket-pair-test.js
rename to test/unit/compat/socket-pair-test.ts
index 0e314418..c6077364 100644
--- a/test/unit/compat/socket-pair-test.js
+++ b/test/unit/compat/socket-pair-test.ts
@@ -1,16 +1,19 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   for (const proto of testProtos("tcp")) {
     describe(`compat socket with ${proto} pair`, function () {
+      let address: string
+      beforeEach(async () => {
+        address = await uniqAddress(proto)
+      })
+
       it("should support pair-pair", function (done) {
         const pairA = zmq.socket("pair")
         const pairB = zmq.socket("pair")
 
-        const address = uniqAddress(proto)
-
         let n = 0
         pairA.monitor()
         pairB.monitor()
diff --git a/test/unit/compat/socket-pub-sub-test.js b/test/unit/compat/socket-pub-sub-test.ts
similarity index 91%
rename from test/unit/compat/socket-pub-sub-test.js
rename to test/unit/compat/socket-pub-sub-test.ts
index 60467ba1..34ba0a87 100644
--- a/test/unit/compat/socket-pub-sub-test.js
+++ b/test/unit/compat/socket-pub-sub-test.ts
@@ -1,20 +1,20 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   for (const proto of testProtos("tcp", "inproc")) {
     describe(`compat socket with ${proto} pub-sub`, function () {
-      let pub
-      let sub
-
-      beforeEach(function () {
+      let pub: zmq.Socket
+      let sub: zmq.Socket
+      let address: string
+      beforeEach(async function () {
         pub = zmq.socket("pub")
         sub = zmq.socket("sub")
+        address = await uniqAddress(proto)
       })
 
       it("should support pub-sub", function (done) {
-        const address = uniqAddress(proto)
         let n = 0
 
         sub.subscribe("")
@@ -60,7 +60,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       })
 
       it("should support pub-sub filter", function (done) {
-        const address = uniqAddress(proto)
         let n = 0
 
         sub.subscribe("js")
@@ -113,12 +112,11 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         })
 
         it("should continue to deliver messages in message handler", function (done) {
-          let error
+          let error: Error
           process.once("uncaughtException", err => {
             error = err
           })
 
-          const address = uniqAddress(proto)
           let n = 0
 
           sub.subscribe("")
diff --git a/test/unit/compat/socket-push-pull-test.js b/test/unit/compat/socket-push-pull-test.ts
similarity index 89%
rename from test/unit/compat/socket-push-pull-test.js
rename to test/unit/compat/socket-push-pull-test.ts
index c589bf8d..789ff382 100644
--- a/test/unit/compat/socket-push-pull-test.js
+++ b/test/unit/compat/socket-push-pull-test.ts
@@ -1,16 +1,19 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   for (const proto of testProtos("tcp", "inproc")) {
     describe(`compat socket with ${proto} push-pull`, function () {
+      let address: string
+      beforeEach(async () => {
+        address = await uniqAddress(proto)
+      })
+
       it("should support push-pull", function (done) {
         const push = zmq.socket("push")
         const pull = zmq.socket("pull")
 
-        const address = uniqAddress(proto)
-
         let n = 0
         pull.on("message", function (msg) {
           assert.instanceOf(msg, Buffer)
@@ -46,8 +49,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         const push = zmq.socket("push")
         const pull = zmq.socket("pull")
 
-        const address = uniqAddress(proto)
-
         let n = 0
 
         pull.on("message", function (msg) {
@@ -81,8 +82,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         const push = zmq.socket("push")
         const pull = zmq.socket("pull")
 
-        const address = uniqAddress(proto)
-
         const messages = ["bar", "foo"]
         pull.bind(address, err => {
           if (err) {
@@ -112,15 +111,13 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         const push = zmq.socket("push")
         const pull = zmq.socket("pull")
 
-        const address = uniqAddress(proto)
-
         let n = 0
 
-        function checkNoMessages(msg) {
+        function checkNoMessages(msg: string) {
           assert.equal(msg, undefined)
         }
 
-        function checkMessages(msg) {
+        function checkMessages(msg: string) {
           assert.instanceOf(msg, Buffer)
           switch (n++) {
             case 0:
diff --git a/test/unit/compat/socket-req-rep-test.js b/test/unit/compat/socket-req-rep-test.ts
similarity index 79%
rename from test/unit/compat/socket-req-rep-test.js
rename to test/unit/compat/socket-req-rep-test.ts
index d83168e0..8086de05 100644
--- a/test/unit/compat/socket-req-rep-test.js
+++ b/test/unit/compat/socket-req-rep-test.ts
@@ -1,17 +1,20 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   for (const proto of testProtos("tcp", "inproc")) {
     describe(`compat socket with ${proto} req-rep`, function () {
+      let address: string
+      beforeEach(async () => {
+        address = await uniqAddress(proto)
+      })
+
       it("should support req-rep", function (done) {
         const rep = zmq.socket("rep")
         const req = zmq.socket("req")
 
-        const address = uniqAddress(proto)
-
-        rep.on("message", function (msg) {
+        rep.on("message", function (msg: string) {
           assert.instanceOf(msg, Buffer)
           assert.equal(msg.toString(), "hello")
           rep.send("world")
@@ -33,15 +36,15 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         })
       })
 
-      it("should support multiple", function (done) {
-        const n = 5
-
-        for (let i = 0; i < n; i++) {
-          ;(function (n) {
+      it("should support multiple", function () {
+        return new Promise<void>(async resolve => {
+          const n = 5
+          for (let i = 0; i < n; i++) {
+            let n = i
             const rep = zmq.socket("rep")
             const req = zmq.socket("req")
 
-            const address = uniqAddress(proto)
+            const address = await uniqAddress(proto)
 
             rep.on("message", function (msg) {
               assert.instanceOf(msg, Buffer)
@@ -61,20 +64,18 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
                 req.close()
                 rep.close()
                 if (!--n) {
-                  done()
+                  resolve()
                 }
               })
             })
-          })(i)
-        }
+          }
+        })
       })
 
       it("should support a burst", function (done) {
         const rep = zmq.socket("rep")
         const req = zmq.socket("req")
 
-        const address = uniqAddress(proto)
-
         const n = 10
 
         rep.on("message", function (msg) {
diff --git a/test/unit/compat/socket-router-test.js b/test/unit/compat/socket-router-test.ts
similarity index 87%
rename from test/unit/compat/socket-router-test.js
rename to test/unit/compat/socket-router-test.ts
index 8413ffb8..bbfe167c 100644
--- a/test/unit/compat/socket-router-test.js
+++ b/test/unit/compat/socket-router-test.ts
@@ -1,10 +1,15 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   for (const proto of testProtos("tcp", "inproc")) {
     describe(`compat socket with ${proto} router`, function () {
+      let address: string
+      beforeEach(async () => {
+        address = await uniqAddress(proto)
+      })
+
       it("should handle unroutable messages", function (done) {
         let complete = 0
 
@@ -16,7 +21,10 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         errMsgs.push("Resource temporarily unavailable")
         errMsgs.push("Host unreachable")
 
-        function assertRouteError(err) {
+        function assertRouteError(err: Error | undefined) {
+          if (err === undefined) {
+            throw new Error("No error was emitted")
+          }
           if (errMsgs.indexOf(err.message) === -1) {
             throw new Error(err.message)
           }
@@ -72,15 +80,12 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       })
 
       it("should handle router-dealer message bursts", function (done) {
-        this.slow(150)
         // tests https://github.com/JustinTulloss/zeromq.node/issues/523
         // based on https://gist.github.com/messa/862638ab44ca65f712fe4d6ef79aeb67
 
         const router = zmq.socket("router")
         const dealer = zmq.socket("dealer")
 
-        const address = uniqAddress(proto)
-
         const expected = 1000
         let counted = 0
 
diff --git a/test/unit/compat/socket-stream-test.js b/test/unit/compat/socket-stream-test.ts
similarity index 78%
rename from test/unit/compat/socket-stream-test.js
rename to test/unit/compat/socket-stream-test.ts
index 6dcb4ace..399380bc 100644
--- a/test/unit/compat/socket-stream-test.js
+++ b/test/unit/compat/socket-stream-test.ts
@@ -1,15 +1,19 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
-  const http = require("http")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {uniqAddress} from "../helpers"
+import http from "http"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   describe("compat socket stream", function () {
+    let address: string
+    beforeEach(async () => {
+      address = await uniqAddress("tcp")
+    })
+
     it("should support a stream socket type", function (done) {
       const stream = zmq.socket("stream")
-      const address = uniqAddress("tcp")
 
-      stream.on("message", function (id, msg) {
+      stream.on("message", function (id: string, msg: string) {
         assert.instanceOf(msg, Buffer)
         if (msg.length == 0) {
           return
@@ -37,7 +41,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         stream.send([id, httpProtocolString])
       })
 
-      stream.bind(address, err => {
+      stream.bind(address, (err: Error | undefined) => {
         if (err) {
           throw err
         }
@@ -46,9 +50,10 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         http.get(
           `${address.replace("tcp:", "http:")}/aRandomRequestPath`,
           function (httpMsg) {
+            // @ts-expect-error
             assert.equal(httpMsg.socket._readableState.reading, false)
 
-            httpMsg.on("data", function (msg) {
+            httpMsg.on("data", function (msg: string) {
               assert.instanceOf(msg, Buffer)
               assert.equal(
                 msg.toString(),
diff --git a/test/unit/compat/socket-test.js b/test/unit/compat/socket-test.ts
similarity index 90%
rename from test/unit/compat/socket-test.js
rename to test/unit/compat/socket-test.ts
index bf8d178f..e8813636 100644
--- a/test/unit/compat/socket-test.js
+++ b/test/unit/compat/socket-test.ts
@@ -1,9 +1,9 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
+import * as zmq from "../../../v5-compat"
+import { assert } from "chai"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   describe("compat socket", function () {
-    let sock
+    let sock: zmq.Socket
 
     beforeEach(function () {
       sock = zmq.socket("req")
diff --git a/test/unit/compat/socket-unbind-test.js b/test/unit/compat/socket-unbind-test.ts
similarity index 73%
rename from test/unit/compat/socket-unbind-test.js
rename to test/unit/compat/socket-unbind-test.ts
index dfb72bb8..612c337e 100644
--- a/test/unit/compat/socket-unbind-test.js
+++ b/test/unit/compat/socket-unbind-test.ts
@@ -1,14 +1,14 @@
 /* This test is very unreliable in practice, especially in CI.
    It is disabled by default. */
+import * as zmq from "../../../v5-compat"
+import semver from "semver"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
+
 if (
-  process.env.INCLUDE_COMPAT_TESTS &&
+  process.env.INCLUDE_COMPAT_TESTS === "true" &&
   process.env.INCLUDE_COMPAT_UNBIND_TEST
 ) {
-  const zmq = require("./load")
-  const semver = require("semver")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
-
   for (const proto of testProtos("tcp")) {
     describe(`compat socket with ${proto} unbind`, function () {
       beforeEach(function () {
@@ -18,14 +18,18 @@ if (
         }
       })
 
-      let sockA
-      let sockB
-      let sockC
+      let sockA: zmq.Socket
+      let sockB: zmq.Socket
+      let sockC: zmq.Socket
+      let address1: string
+      let address2: string
 
-      beforeEach(function () {
+      beforeEach(async function () {
         sockA = zmq.socket("dealer", {linger: 0})
         sockB = zmq.socket("dealer", {linger: 0})
         sockC = zmq.socket("dealer", {linger: 0})
+        address1 = await uniqAddress(proto)
+        address2 = await uniqAddress(proto)
       })
 
       afterEach(function () {
@@ -35,14 +39,11 @@ if (
       })
 
       it("should be able to unbind", function (done) {
-        const address1 = uniqAddress(proto)
-        const address2 = uniqAddress(proto)
-
         let msgCount = 0
         sockA.bindSync(address1)
         sockA.bindSync(address2)
 
-        sockA.on("unbind", async function (addr) {
+        sockA.on("unbind", async function (addr: string) {
           if (addr === address1) {
             sockB.send("Error from sockB.")
             sockC.send("Messsage from sockC.")
@@ -50,7 +51,7 @@ if (
           }
         })
 
-        sockA.on("message", async function (msg) {
+        sockA.on("message", async function (msg: {toString: () => string}) {
           msgCount++
           if (msg.toString() === "Hello from sockB.") {
             sockA.unbindSync(address1)
diff --git a/test/unit/compat/socket-xpub-xsub-test.js b/test/unit/compat/socket-xpub-xsub-test.ts
similarity index 88%
rename from test/unit/compat/socket-xpub-xsub-test.js
rename to test/unit/compat/socket-xpub-xsub-test.ts
index f101a94c..3828af9c 100644
--- a/test/unit/compat/socket-xpub-xsub-test.js
+++ b/test/unit/compat/socket-xpub-xsub-test.ts
@@ -1,9 +1,17 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   for (const proto of testProtos("tcp", "inproc")) {
+    let address1: string
+    let address2: string
+
+    beforeEach(async function () {
+      address1 = await uniqAddress(proto)
+      address2 = await uniqAddress(proto)
+    })
+
     describe(`compat socket with ${proto} xpub-xsub`, function () {
       it("should support pub-sub tracing and filtering", function (done) {
         let n = 0
@@ -13,9 +21,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         const xpub = zmq.socket("xpub")
         const xsub = zmq.socket("xsub")
 
-        const address1 = uniqAddress(proto)
-        const address2 = uniqAddress(proto)
-
         pub.bind(address1, err => {
           if (err) {
             throw err
diff --git a/test/unit/compat/socket-zap-test.js b/test/unit/compat/socket-zap-test.ts
similarity index 82%
rename from test/unit/compat/socket-zap-test.js
rename to test/unit/compat/socket-zap-test.ts
index 583e5b89..cc9a16ce 100644
--- a/test/unit/compat/socket-zap-test.js
+++ b/test/unit/compat/socket-zap-test.ts
@@ -1,9 +1,10 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const semver = require("semver")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {capability} from "../../../src"
+import semver from "semver"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   function start() {
     const zap = zmq.socket("router")
 
@@ -49,7 +50,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       )
     })
 
-    return new Promise((resolve, reject) => {
+    return new Promise<zmq.Socket>((resolve, reject) => {
       zap.bind("inproc://zeromq.zap.01", err => {
         if (err) {
           return reject(err)
@@ -61,9 +62,10 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
 
   for (const proto of testProtos("tcp", "inproc")) {
     describe(`compat socket with ${proto} zap`, function () {
-      let zapSocket
-      let rep
-      let req
+      let zapSocket: zmq.Socket
+      let rep: zmq.Socket
+      let req: zmq.Socket
+      let address: string
 
       before(async function () {
         zapSocket = await start()
@@ -76,7 +78,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         })
       })
 
-      beforeEach(function () {
+      beforeEach(async function () {
         /* Since ZAP uses inproc transport, it does not work reliably. */
         if (semver.satisfies(zmq.version, "< 4.2")) {
           this.skip()
@@ -84,6 +86,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
 
         rep = zmq.socket("rep")
         req = zmq.socket("req")
+        address = await uniqAddress(proto)
       })
 
       afterEach(function () {
@@ -92,11 +95,10 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       })
 
       it("should support curve", function (done) {
-        if (!zmq.capability.curve) {
+        if (!capability.curve) {
           this.skip()
         }
 
-        const address = uniqAddress(proto)
         const serverPublicKey = Buffer.from(
           "7f188e5244b02bf497b86de417515cf4d4053ce4eb977aee91a55354655ec33a",
           "hex",
@@ -114,7 +116,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
           "hex",
         )
 
-        rep.on("message", function (msg) {
+        rep.on("message", function (msg: unknown) {
           assert.instanceOf(msg, Buffer)
           assert.equal(msg.toString(), "hello")
           rep.send("world")
@@ -125,7 +127,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         rep.curve_secretkey = serverPrivateKey
         assert.equal(rep.mechanism, 2)
 
-        rep.bind(address, err => {
+        rep.bind(address, (err: any) => {
           if (err) {
             throw err
           }
@@ -136,7 +138,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
 
           req.connect(address)
           req.send("hello")
-          req.on("message", function (msg) {
+          req.on("message", function (msg: unknown) {
             assert.instanceOf(msg, Buffer)
             assert.equal(msg.toString(), "world")
             done()
@@ -145,9 +147,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       })
 
       it("should support null", function (done) {
-        const address = uniqAddress(proto)
-
-        rep.on("message", function (msg) {
+        rep.on("message", function (msg: unknown) {
           assert.instanceOf(msg, Buffer)
           assert.equal(msg.toString(), "hello")
           rep.send("world")
@@ -156,14 +156,14 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         rep.zap_domain = "test"
         assert.equal(rep.mechanism, 0)
 
-        rep.bind(address, err => {
+        rep.bind(address, (err: any) => {
           if (err) {
             throw err
           }
           assert.equal(req.mechanism, 0)
           req.connect(address)
           req.send("hello")
-          req.on("message", function (msg) {
+          req.on("message", function (msg: unknown) {
             assert.instanceOf(msg, Buffer)
             assert.equal(msg.toString(), "world")
             done()
@@ -172,9 +172,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       })
 
       it("should support plain", function (done) {
-        const address = uniqAddress(proto)
-
-        rep.on("message", function (msg) {
+        rep.on("message", function (msg: unknown) {
           assert.instanceOf(msg, Buffer)
           assert.equal(msg.toString(), "hello")
           rep.send("world")
@@ -184,7 +182,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         rep.plain_server = 1
         assert.equal(rep.mechanism, 1)
 
-        rep.bind(address, err => {
+        rep.bind(address, (err: any) => {
           if (err) {
             throw err
           }
@@ -194,7 +192,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
 
           req.connect(address)
           req.send("hello")
-          req.on("message", function (msg) {
+          req.on("message", function (msg: unknown) {
             assert.instanceOf(msg, Buffer)
             assert.equal(msg.toString(), "world")
             done()
diff --git a/test/unit/compat/zmq-proxy-push-pull-test.js b/test/unit/compat/zmq-proxy-push-pull-test.ts
similarity index 82%
rename from test/unit/compat/zmq-proxy-push-pull-test.js
rename to test/unit/compat/zmq-proxy-push-pull-test.ts
index 41837694..e4606608 100644
--- a/test/unit/compat/zmq-proxy-push-pull-test.js
+++ b/test/unit/compat/zmq-proxy-push-pull-test.ts
@@ -1,22 +1,28 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   for (const proto of testProtos("tcp")) {
     describe(`compat proxy with ${proto} push-pull`, function () {
-      const sockets = []
+      const sockets: zmq.Socket[] = []
+      let frontendAddr: string
+      let backendAddr: string
+      let captureAddr: string
+
+      beforeEach(async function () {
+        frontendAddr = await uniqAddress(proto)
+        backendAddr = await uniqAddress(proto)
+        captureAddr = await uniqAddress(proto)
+      })
 
       afterEach(function () {
-        while (sockets.length) {
-          sockets.pop().close()
+        if (sockets.length) {
+          sockets.pop()?.close()
         }
       })
 
       it("should proxy push-pull connected to pull-push", function (done) {
-        const frontendAddr = uniqAddress(proto)
-        const backendAddr = uniqAddress(proto)
-
         const frontend = zmq.socket("pull")
         const backend = zmq.socket("push")
 
@@ -48,10 +54,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       })
 
       it("should proxy pull-push connected to push-pull with capture", function (done) {
-        const frontendAddr = uniqAddress(proto)
-        const backendAddr = uniqAddress(proto)
-        const captureAddr = uniqAddress(proto)
-
         const frontend = zmq.socket("push")
         const backend = zmq.socket("pull")
 
diff --git a/test/unit/compat/zmq-proxy-router-dealer-test.js b/test/unit/compat/zmq-proxy-router-dealer-test.ts
similarity index 84%
rename from test/unit/compat/zmq-proxy-router-dealer-test.js
rename to test/unit/compat/zmq-proxy-router-dealer-test.ts
index 148412dd..d5ee4e5f 100644
--- a/test/unit/compat/zmq-proxy-router-dealer-test.js
+++ b/test/unit/compat/zmq-proxy-router-dealer-test.ts
@@ -1,22 +1,28 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   for (const proto of testProtos("tcp")) {
     describe(`compat proxy with ${proto} router-dealer`, function () {
-      const sockets = []
+      const sockets: zmq.Socket[] = []
+      let frontendAddr: string
+      let backendAddr: string
+      let captureAddr: string
+
+      beforeEach(async function () {
+        frontendAddr = await uniqAddress(proto)
+        backendAddr = await uniqAddress(proto)
+        captureAddr = await uniqAddress(proto)
+      })
 
       afterEach(function () {
         while (sockets.length) {
-          sockets.pop().close()
+          sockets.pop()?.close()
         }
       })
 
       it("should proxy req-rep connected over router-dealer", function (done) {
-        const frontendAddr = uniqAddress(proto)
-        const backendAddr = uniqAddress(proto)
-
         const frontend = zmq.socket("router")
         const backend = zmq.socket("dealer")
 
@@ -53,10 +59,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       })
 
       it("should proxy rep-req connections with capture", function (done) {
-        const frontendAddr = uniqAddress(proto)
-        const backendAddr = uniqAddress(proto)
-        const captureAddr = uniqAddress(proto)
-
         const frontend = zmq.socket("router")
         const backend = zmq.socket("dealer")
 
diff --git a/test/unit/compat/zmq-proxy-test.js b/test/unit/compat/zmq-proxy-test.ts
similarity index 58%
rename from test/unit/compat/zmq-proxy-test.js
rename to test/unit/compat/zmq-proxy-test.ts
index 8146a89f..40b1ffed 100644
--- a/test/unit/compat/zmq-proxy-test.js
+++ b/test/unit/compat/zmq-proxy-test.ts
@@ -1,7 +1,7 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   describe("compat proxy", function () {
     it("should be a function off the module namespace", function () {
       assert.typeOf(zmq.proxy, "function")
diff --git a/test/unit/compat/zmq-proxy-xpub-xsub-test.js b/test/unit/compat/zmq-proxy-xpub-xsub-test.ts
similarity index 83%
rename from test/unit/compat/zmq-proxy-xpub-xsub-test.js
rename to test/unit/compat/zmq-proxy-xpub-xsub-test.ts
index c0580fca..e0eb2a6b 100644
--- a/test/unit/compat/zmq-proxy-xpub-xsub-test.js
+++ b/test/unit/compat/zmq-proxy-xpub-xsub-test.ts
@@ -1,22 +1,30 @@
-if (process.env.INCLUDE_COMPAT_TESTS) {
-  const zmq = require("./load")
-  const {assert} = require("chai")
-  const {testProtos, uniqAddress} = require("../helpers")
+import * as zmq from "../../../v5-compat"
+import {assert} from "chai"
+import {testProtos, uniqAddress} from "../helpers"
+import {isFullError} from "../../../src/errors"
 
+if (process.env.INCLUDE_COMPAT_TESTS === "true") {
   for (const proto of testProtos("tcp")) {
     describe(`compat proxy with ${proto} xpub-xsub`, function () {
-      const sockets = []
+      const sockets: zmq.Socket[] = []
+
+      let frontendAddr: string
+      let backendAddr: string
+      let captureAddr: string
+
+      beforeEach(async function () {
+        frontendAddr = await uniqAddress(proto)
+        backendAddr = await uniqAddress(proto)
+        captureAddr = await uniqAddress(proto)
+      })
 
       afterEach(function () {
         while (sockets.length) {
-          sockets.pop().close()
+          sockets.pop()?.close()
         }
       })
 
       it("should proxy pub-sub connected to xpub-xsub", function (done) {
-        const frontendAddr = uniqAddress(proto)
-        const backendAddr = uniqAddress(proto)
-
         const frontend = zmq.socket("xpub")
         const backend = zmq.socket("xsub")
 
@@ -50,10 +58,6 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
       })
 
       it("should proxy connections with capture", function (done) {
-        const frontendAddr = uniqAddress(proto)
-        const backendAddr = uniqAddress(proto)
-        const captureAddr = uniqAddress(proto)
-
         const frontend = zmq.socket("xpub")
         const backend = zmq.socket("xsub")
 
@@ -119,6 +123,7 @@ if (process.env.INCLUDE_COMPAT_TESTS) {
         try {
           zmq.proxy(backend, frontend)
         } catch (err) {
+          assert(isFullError(err))
           assert.include(
             [
               "wrong socket order to proxy",
diff --git a/test/unit/context-process-exit-test.ts b/test/unit/context-process-exit-test.ts
index 9aeda4fe..c5f9ae79 100644
--- a/test/unit/context-process-exit-test.ts
+++ b/test/unit/context-process-exit-test.ts
@@ -7,7 +7,6 @@ import {createProcess} from "./helpers"
 describe("context process exit", function () {
   describe("with default context", function () {
     it("should occur when sockets are closed", async function () {
-      this.slow(200)
       const {code} = await createProcess(() => {
         const socket1 = new zmq.Dealer()
         socket1.close()
@@ -19,7 +18,6 @@ describe("context process exit", function () {
     })
 
     it("should occur when sockets are not closed", async function () {
-      this.slow(200)
       const {code} = await createProcess(() => {
         const socket1 = new zmq.Dealer()
         const socket2 = new zmq.Router()
@@ -29,7 +27,6 @@ describe("context process exit", function () {
     })
 
     it("should not occur when sockets are open and polling", async function () {
-      this.slow(1000)
       const {code, isTimeout} = await createProcess(() => {
         const socket1 = new zmq.Dealer()
         socket1.connect("inproc://foo")
@@ -43,7 +40,6 @@ describe("context process exit", function () {
     })
 
     it("should produce warning when messages are queued with blocky", async function () {
-      this.slow(2000)
       const {stderr} = await createProcess(() => {
         zmq.context.blocky = true
         const socket1 = new zmq.Dealer({linger: 1000})
@@ -67,7 +63,6 @@ describe("context process exit", function () {
     })
 
     it("should produce warning when messages are queued without blocky", async function () {
-      this.slow(2000)
       const {stderr} = await createProcess(() => {
         zmq.context.blocky = false
         const socket1 = new zmq.Dealer({linger: 1000})
@@ -84,7 +79,6 @@ describe("context process exit", function () {
     })
 
     it("should not produce warning when messages are queued for a short time", async function () {
-      this.slow(1000)
       const {stderr} = await createProcess(() => {
         zmq.context.blocky = true
         const socket1 = new zmq.Dealer({linger: 50})
@@ -100,7 +94,6 @@ describe("context process exit", function () {
 
   describe("with custom context", function () {
     it("should occur when sockets are closed", async function () {
-      this.slow(200)
       const {code} = await createProcess(() => {
         const context = new zmq.Context()
         const socket1 = new zmq.Dealer({context})
@@ -113,7 +106,6 @@ describe("context process exit", function () {
     })
 
     it("should occur when sockets are closed and context is gced", async function () {
-      this.slow(200)
       const {code} = await createProcess(() => {
         function run() {
           const context = new zmq.Context()
@@ -131,7 +123,6 @@ describe("context process exit", function () {
     })
 
     it("should occur when sockets are not closed", async function () {
-      this.slow(200)
       const {code} = await createProcess(() => {
         const context = new zmq.Context()
         const socket1 = new zmq.Dealer({context})
@@ -142,7 +133,6 @@ describe("context process exit", function () {
     })
 
     it("should not occur when sockets are open and polling", async function () {
-      this.slow(1000)
       const {code, isTimeout} = await createProcess(() => {
         const context = new zmq.Context()
         const socket1 = new zmq.Dealer({context})
diff --git a/test/unit/context-thread-test.ts b/test/unit/context-thread-test.ts
index 3d44a206..0d4b0208 100644
--- a/test/unit/context-thread-test.ts
+++ b/test/unit/context-thread-test.ts
@@ -5,9 +5,6 @@ import {assert} from "chai"
 import {createWorker} from "./helpers"
 
 describe("context in thread", function () {
-  this.slow(2000)
-  this.timeout(5000)
-
   beforeEach(function () {
     /* Node.js worker support introduced in version 10.5. */
     if (semver.satisfies(process.versions.node, "< 10.5")) {
diff --git a/test/unit/helpers.ts b/test/unit/helpers.ts
index 5186f8de..005f50ec 100644
--- a/test/unit/helpers.ts
+++ b/test/unit/helpers.ts
@@ -19,7 +19,7 @@ if (semver.satisfies(zmq.version, ">= 4.2")) {
  */
 let idFallback = 5000
 async function getUniqueId() {
-  const idPath = path.resolve(__dirname, "../../tmp/id")
+  const idPath = path.resolve(__dirname, "../../tmp/port-id.lock")
   await fs.promises.mkdir(path.dirname(idPath), {recursive: true})
 
   try {
diff --git a/test/unit/proxy-router-dealer-test.ts b/test/unit/proxy-router-dealer-test.ts
index f5d9a67f..51e3d945 100644
--- a/test/unit/proxy-router-dealer-test.ts
+++ b/test/unit/proxy-router-dealer-test.ts
@@ -89,13 +89,16 @@ for (const proto of testProtos("tcp", "ipc", "inproc")) {
           rep.close()
         }
 
-        console.log("waiting for messages")
+        console.log(
+          `waiting for messages for proxy with ${proto} router/dealer...`,
+        )
 
         await Promise.all([echo(), send()])
         assert.deepEqual(received, messages)
 
         proxy.terminate()
         await done
+        console.log(`Done proxying with ${proto} router/dealer`)
       })
     })
   })
diff --git a/test/unit/socket-close-test.ts b/test/unit/socket-close-test.ts
index 83f145b5..3e92fab2 100644
--- a/test/unit/socket-close-test.ts
+++ b/test/unit/socket-close-test.ts
@@ -108,7 +108,6 @@ for (const proto of testProtos("tcp", "ipc", "inproc")) {
 
       it("should release reference to context", async function () {
         const gc = getGcOrSkipTest(this)
-        this.slow(200)
 
         let weakRef: undefined | WeakRef<zmq.Context>
 
@@ -138,7 +137,7 @@ for (const proto of testProtos("tcp", "ipc", "inproc")) {
     //     if (process.env.SKIP_GC_FINALIZER_TESTS) {
     //       this.skip()
     //     }
-    //     this.slow(200)
+    //
 
     //     let weakRef: undefined | WeakRef<zmq.Context>
     //     const task = async () => {
diff --git a/test/unit/socket-events-test.ts b/test/unit/socket-events-test.ts
index bf294a60..bef10ebd 100644
--- a/test/unit/socket-events-test.ts
+++ b/test/unit/socket-events-test.ts
@@ -54,7 +54,6 @@ for (const proto of testProtos("tcp", "ipc", "inproc")) {
         })
 
         it("should receive connect events", async function () {
-          this.slow(250)
           const address = await uniqAddress(proto)
 
           const [event] = await Promise.all([
diff --git a/test/unit/socket-process-exit-test.ts b/test/unit/socket-process-exit-test.ts
index 2d3392fb..22a4c9be 100644
--- a/test/unit/socket-process-exit-test.ts
+++ b/test/unit/socket-process-exit-test.ts
@@ -6,7 +6,6 @@ import {createProcess} from "./helpers"
 describe("socket process exit", function () {
   /* Reported: https://github.com/nodejs/node-addon-api/issues/591 */
   it.skip("should occur cleanly when sending in exit hook", async function () {
-    this.slow(200)
     const {code} = await createProcess(async () => {
       const sockA = new zmq.Pair()
       const sockB = new zmq.Pair()
@@ -24,7 +23,6 @@ describe("socket process exit", function () {
   })
 
   it("should occur cleanly when sending on unbound socket", async function () {
-    this.slow(200)
     const {code} = await createProcess(async () => {
       const sock = new zmq.Publisher()
       await sock.send("test")
@@ -34,7 +32,6 @@ describe("socket process exit", function () {
   })
 
   it("should not occur when sending and blocked on unbound socket", async function () {
-    this.slow(1000)
     const {code} = await createProcess(async () => {
       const sock = new zmq.Dealer()
       await sock.send("test")
@@ -44,7 +41,6 @@ describe("socket process exit", function () {
   })
 
   it("should occur cleanly on socket close when reading events", async function () {
-    this.slow(200)
     const {code} = await createProcess(() => {
       const sock = new zmq.Dealer()
 
@@ -63,7 +59,6 @@ describe("socket process exit", function () {
   })
 
   it("should not occur while reading events", async function () {
-    this.slow(1000)
     const {code} = await createProcess(async () => {
       const sock = new zmq.Dealer()
 
diff --git a/test/unit/socket-send-receive-test.ts b/test/unit/socket-send-receive-test.ts
index bdd22871..508fab57 100644
--- a/test/unit/socket-send-receive-test.ts
+++ b/test/unit/socket-send-receive-test.ts
@@ -265,8 +265,6 @@ for (const proto of testProtos("tcp", "ipc", "inproc")) {
       })
 
       it("should poll simultaneously", async function () {
-        this.timeout(5000)
-
         const sendReceiveA = async () => {
           const [msg1] = await Promise.all([
             sockA.receive(),
@@ -426,8 +424,6 @@ for (const proto of testProtos("tcp", "ipc", "inproc")) {
       }
 
       it("should not starve event loop", async function () {
-        this.slow(250)
-
         sockA.sendHighWaterMark = 5000
         sockB.receiveHighWaterMark = 5000
 
diff --git a/test/unit/socket-thread-test.ts b/test/unit/socket-thread-test.ts
index 290847b3..9d581780 100644
--- a/test/unit/socket-thread-test.ts
+++ b/test/unit/socket-thread-test.ts
@@ -6,9 +6,6 @@ import {createWorker, testProtos, uniqAddress} from "./helpers"
 
 for (const proto of testProtos("tcp", "ipc", "inproc")) {
   describe(`socket with ${proto} in thread`, function () {
-    this.slow(2000)
-    this.timeout(5000)
-
     beforeEach(function () {
       /* Node.js worker support introduced in version 10.5. */
       if (semver.satisfies(process.versions.node, "< 10.5")) {
diff --git a/test/unit/socket-zap-test.ts b/test/unit/socket-zap-test.ts
index 113c23f4..53fa9fbc 100644
--- a/test/unit/socket-zap-test.ts
+++ b/test/unit/socket-zap-test.ts
@@ -167,8 +167,6 @@ for (const proto of testProtos("tcp", "ipc")) {
           this.skip()
         }
 
-        this.slow(250)
-
         sockA.plainServer = true
         sockB.curveServer = true
 
diff --git a/test/unit/typings-compatibility-test.ts b/test/unit/typings-compatibility-test.ts
index 86af58d1..1c2ee070 100644
--- a/test/unit/typings-compatibility-test.ts
+++ b/test/unit/typings-compatibility-test.ts
@@ -100,7 +100,6 @@ describe("compatibility of typings for typescript versions", async function () {
   let execCmd: string
 
   before(async function () {
-    this.timeout(10000)
     if (/^true$/.test(process.env.EXCLUDE_TYPINGS_COMPAT_TESTS as string)) {
       this.skip()
     }
@@ -110,7 +109,6 @@ describe("compatibility of typings for typescript versions", async function () {
   for (const tsVer of tsVersions) {
     // must increase timeout for allowing `npm install`'ing the version of
     // the typescript package to complete
-    this.timeout(30000)
 
     const tscTargetPath = path.resolve(
       tscTestBasePath,
diff --git a/tsconfig.json b/tsconfig.json
index 5f6b4dde..e21bbb36 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -19,6 +19,11 @@
     "incremental": true,
     "sourceMap": true,
     "esModuleInterop": true,
-    "lib": ["ES2020"]
-  }
+    "lib": [
+      "ES2020",
+      // only used in tests
+      "ES2021.WeakRef"
+    ]
+  },
+  "compileOnSave": true
 }