diff --git a/Readme.md b/Readme.md
index 2f35e7f2..a8f1674f 100644
--- a/Readme.md
+++ b/Readme.md
@@ -282,7 +282,7 @@ The options accepted have keys corresponding to the options described in [CLI Ar
   mkdir: true, // create the target destination
 
 
-  customPrettifiers: {}
+  customPrettifiers: new Map()
 }
 ```
 
@@ -293,16 +293,16 @@ The defaults for `sync`, `append`, `mkdir` inherit from
 [`SonicBoom(opts)`](https://github.com/pinojs/sonic-boom#API).
 
 `customPrettifiers` option provides the ability to add a custom prettify function
-for specific log properties. `customPrettifiers` is an object, where keys are
-log properties that will be prettified and value is the prettify function itself.
+for specific log properties. `customPrettifiers` is a Map, where keys are log
+properties that will be prettified and value is the prettify function itself.
 For example, if a log line contains a `query` property,
 you can specify a prettifier for it:
 
 ```js
 {
-  customPrettifiers: {
-    query: prettifyQuery
-  }
+  customPrettifiers: new Map([
+    ['query', prettifyQuery]
+  ])
 }
 //...
 const prettifyQuery = value => {
@@ -330,27 +330,27 @@ An example usage of `customPrettifiers` using all parameters from the function s
 
 ```js
 {
-  customPrettifiers: {
+  customPrettifiers: new Map([
     // The argument for this function will be the same
     // string that's at the start of the log-line by default:
-    time: timestamp => `🕰 ${timestamp}`,
+    ['time', timestamp => `🕰 ${timestamp}`],
 
     // The argument for the level-prettifier may vary depending
     // on if the levelKey option is used or not.
     // By default this will be the same numerics as the Pino default:
-    level: logLevel => `LEVEL: ${logLevel}`,
+    ['level', logLevel => `LEVEL: ${logLevel}`],
     // level provides additional data in `extras`:
     // * label => derived level label string
     // * labelColorized => derived level label string with colorette colors applied based on customColors and whether colors are supported
-    level: (logLevel, key, log, { label, labelColorized, colors }) => `LEVEL: ${logLevel} LABEL: ${levelLabel} COLORIZED LABEL: ${labelColorized}`,
+    ['level', (logLevel, key, log, { label, labelColorized, colors }) => `LEVEL: ${logLevel} LABEL: ${levelLabel} COLORIZED LABEL: ${labelColorized}`],
 
     // other prettifiers can be used for the other keys if needed, for example
-    hostname: hostname => `MY HOST: ${hostname}`,
-    pid: pid => pid,
-    name: (name, key, log, { colors }) => `${colors.blue(name)}`,
-    caller: (caller, key, log, { colors }) => `${colors.greenBright(caller)}`,
-    myCustomLogProp: (value, key, log, { colors }) => `My Prop -> ${colors.bold(value)} <--`
-  }
+    ['hostname', hostname => `MY HOST: ${hostname}`],
+    ['pid', pid => pid],
+    ['name', (name, key, log, { colors }) => `${colors.blue(name)}`],
+    ['caller', (caller, key, log, { colors }) => `${colors.greenBright(caller)}`],
+    ['myCustomLogProp', (value, key, log, { colors }) => `My Prop -> ${colors.bold(value)} <--`]
+  ])
 }
 ```
 
diff --git a/benchmark.js b/benchmark.js
index aaf7412e..43825bc0 100644
--- a/benchmark.js
+++ b/benchmark.js
@@ -51,14 +51,14 @@ const run = bench([
 
   function customPrettifiers (cb) {
     const pretty = prettyFactory({
-      customPrettifiers: {
-        time (tstamp) {
+      customPrettifiers: new Map([
+        ['time', (tstamp) => {
           return tstamp
-        },
-        pid () {
+        }],
+        ['pid', () => {
           return ''
-        }
-      }
+        }]
+      ])
     })
     const input = `{"time":${tstampMillis},"pid":1,"hostname":"foo","msg":"benchmark","foo":"foo","bar":{"bar":"bar"}}\n`
     for (var i = 0; i < max; i += 1) {
diff --git a/index.d.ts b/index.d.ts
index 8aa35ca0..c488e396 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -165,17 +165,17 @@ declare namespace PinoPretty {
     mkdir?: boolean;
     /**
      * Provides the ability to add a custom prettify function for specific log properties.
-     * `customPrettifiers` is an object, where keys are log properties that will be prettified
+     * `customPrettifiers` is a Map, where keys are log properties that will be prettified
      * and value is the prettify function itself.
      * For example, if a log line contains a query property, you can specify a prettifier for it:
-     * @default {}
+     * @default new Map()
      *
      * @example
      * ```typescript
      * {
-     *   customPrettifiers: {
-     *     query: prettifyQuery
-     *   }
+     *   customPrettifiers: new Map([
+     *     ['query', prettifyQuery]
+     *   ])
      * }
      * //...
      * const prettifyQuery = value => {
@@ -183,10 +183,7 @@ declare namespace PinoPretty {
      * }
      * ```
      */
-    customPrettifiers?: Record<string, Prettifier> &
-      {
-        level?: Prettifier
-      };
+    customPrettifiers?: CustomPrettifiers;
     /**
      * Change the level names and values to an user custom preset.
      *
@@ -218,8 +215,10 @@ declare namespace PinoPretty {
 
   function build(options: PrettyOptions): PrettyStream;
 
-  type Prettifier = (inputData: string | object, key: string, log: object, extras: PrettifierExtras) => string;
-  type PrettifierExtras = {colors: Colorette.Colorette, label: string, labelColorized: string};
+  type CustomPrettifiers = Map<'level', Prettifier<LevelPrettifierExtras>> & Map<string, Prettifier>
+  type Prettifier<T = object> = (inputData: string | object, key: string, log: object, extras: PrettifierExtras<T>) => string;
+  type PrettifierExtras<T = object> = {colors: Colorette.Colorette} & T;
+  type LevelPrettifierExtras = {label: string, labelColorized: string}
   type MessageFormatFunc = (log: LogDescriptor, messageKey: string, levelLabel: string, extras: PrettifierExtras) => string;
   type PrettyStream = Transform & OnUnknown;
   type ColorizerFactory = typeof colorizerFactory;
@@ -227,7 +226,7 @@ declare namespace PinoPretty {
   type Build = typeof build;
   type isColorSupported = typeof Colorette.isColorSupported;
 
-  export { build, PinoPretty, PrettyOptions, PrettyStream, colorizerFactory, prettyFactory, isColorSupported };
+  export { build, PinoPretty, PrettyOptions, CustomPrettifiers, PrettyStream, colorizerFactory, prettyFactory, isColorSupported };
 }
 
 export = PinoPretty;
diff --git a/index.js b/index.js
index 528b2b0c..3bfeecc2 100644
--- a/index.js
+++ b/index.js
@@ -30,7 +30,7 @@ const pretty = require('./lib/pretty')
  * to use for specific level labels, e.g. `err:red,info:blue`.
  * @property {string|null} [customLevels=null] A comma separated list of user
  * defined level names and numbers, e.g. `err:99,info:1`.
- * @property {CustomPrettifiers} [customPrettifiers={}] A set of prettifier
+ * @property {CustomPrettifiers} [customPrettifiers=Map] A set of prettifier
  * functions to apply to keys defined in this object.
  * @property {K_ERROR_LIKE_KEYS} [errorLikeObjectKeys] A list of string property
  * names to consider as error objects.
@@ -83,7 +83,7 @@ const defaultOptions = {
   crlf: false,
   customColors: null,
   customLevels: null,
-  customPrettifiers: {},
+  customPrettifiers: new Map(),
   errorLikeObjectKeys: ERROR_LIKE_KEYS,
   errorProps: '',
   hideObject: false,
diff --git a/lib/utils/index.js b/lib/utils/index.js
index e083d737..48ebcf09 100644
--- a/lib/utils/index.js
+++ b/lib/utils/index.js
@@ -34,13 +34,13 @@ module.exports = {
 // doc blocks, so we are picking this file as the answer.
 
 /**
- * A hash of log property names mapped to prettifier functions. When the
+ * A map of log property names mapped to prettifier functions. When the
  * incoming log data is being processed for prettification, any key on the log
  * that matches a key in a custom prettifiers hash will be prettified using
  * that matching custom prettifier. The value passed to the custom prettifier
  * will the value associated with the corresponding log key.
  *
- * The hash may contain any arbitrary keys for arbitrary log properties, but it
+ * The map may contain any arbitrary keys for arbitrary log properties, but it
  * may also contain a set of predefined key names that map to well-known log
  * properties. These keys are:
  *
@@ -52,7 +52,7 @@ module.exports = {
  * + `name`
  * + `caller`
  *
- * @typedef {Object.<string, CustomPrettifierFunc>} CustomPrettifiers
+ * @typedef {Map<string, CustomPrettifierFunc>} CustomPrettifiers
  */
 
 /**
diff --git a/lib/utils/parse-factory-options.js b/lib/utils/parse-factory-options.js
index 3b051f03..8fc327bf 100644
--- a/lib/utils/parse-factory-options.js
+++ b/lib/utils/parse-factory-options.js
@@ -25,7 +25,7 @@ const handleLevelLabelData = require('./get-level-label-data')
  * e.g. `{ 30: "info" }`.
  * @property {object} customLevels A hash of level names to level numbers,
  * e.g. `{ info: 30 }`.
- * @property {CustomPrettifiers} customPrettifiers A hash of custom prettifier
+ * @property {CustomPrettifiers} customPrettifiers A map of custom prettifier
  * functions.
  * @property {object} customProperties Comprised of `customLevels` and
  * `customLevelNames` if such options are provided.
diff --git a/lib/utils/prettify-error-log.test.js b/lib/utils/prettify-error-log.test.js
index 04e10f82..d1048002 100644
--- a/lib/utils/prettify-error-log.test.js
+++ b/lib/utils/prettify-error-log.test.js
@@ -10,7 +10,7 @@ const {
 const context = {
   EOL: '\n',
   IDENT: '    ',
-  customPrettifiers: {},
+  customPrettifiers: new Map(),
   errorLikeObjectKeys: ERROR_LIKE_KEYS,
   errorProps: [],
   messageKey: MESSAGE_KEY
diff --git a/lib/utils/prettify-level.js b/lib/utils/prettify-level.js
index 2e4dce84..e401a38b 100644
--- a/lib/utils/prettify-level.js
+++ b/lib/utils/prettify-level.js
@@ -29,7 +29,7 @@ function prettifyLevel ({ log, context }) {
     levelKey,
     getLevelLabelData
   } = context
-  const prettifier = context.customPrettifiers?.level
+  const prettifier = context.customPrettifiers?.get('level')
   const output = getPropertyValue(log, levelKey)
   if (output === undefined) return undefined
   const labelColorized = colorizer(output, { customLevels, customLevelNames })
diff --git a/lib/utils/prettify-level.test.js b/lib/utils/prettify-level.test.js
index e6e5a3c1..1ce01089 100644
--- a/lib/utils/prettify-level.test.js
+++ b/lib/utils/prettify-level.test.js
@@ -63,7 +63,9 @@ tap.test('passes output through provided prettifier', async t => {
     log,
     context: {
       ...context,
-      customPrettifiers: { level () { return 'modified' } }
+      customPrettifiers: new Map([
+        ['level', () => { return 'modified' }]
+      ])
     }
   })
   t.equal(colorized, 'modified')
diff --git a/lib/utils/prettify-metadata.js b/lib/utils/prettify-metadata.js
index 72483b14..0aab43fa 100644
--- a/lib/utils/prettify-metadata.js
+++ b/lib/utils/prettify-metadata.js
@@ -28,14 +28,14 @@ function prettifyMetadata ({ log, context }) {
     line += '('
 
     if (log.name) {
-      line += prettifiers.name
-        ? prettifiers.name(log.name, 'name', log, { colors: colorizer.colors })
+      line += prettifiers.get('name')
+        ? prettifiers.get('name')(log.name, 'name', log, { colors: colorizer.colors })
         : log.name
     }
 
     if (log.pid) {
-      const prettyPid = prettifiers.pid
-        ? prettifiers.pid(log.pid, 'pid', log, { colors: colorizer.colors })
+      const prettyPid = prettifiers.get('pid')
+        ? prettifiers.get('pid')(log.pid, 'pid', log, { colors: colorizer.colors })
         : log.pid
       if (log.name && log.pid) {
         line += '/' + prettyPid
@@ -47,8 +47,8 @@ function prettifyMetadata ({ log, context }) {
     if (log.hostname) {
       // If `pid` and `name` were in the ignore keys list then we don't need
       // the leading space.
-      const prettyHostname = prettifiers.hostname
-        ? prettifiers.hostname(log.hostname, 'hostname', log, { colors: colorizer.colors })
+      const prettyHostname = prettifiers.get('hostname')
+        ? prettifiers.get('hostname')(log.hostname, 'hostname', log, { colors: colorizer.colors })
         : log.hostname
 
       line += `${line === '(' ? 'on' : ' on'} ${prettyHostname}`
@@ -58,8 +58,8 @@ function prettifyMetadata ({ log, context }) {
   }
 
   if (log.caller) {
-    const prettyCaller = prettifiers.caller
-      ? prettifiers.caller(log.caller, 'caller', log, { colors: colorizer.colors })
+    const prettyCaller = prettifiers.get('caller')
+      ? prettifiers.get('caller')(log.caller, 'caller', log, { colors: colorizer.colors })
       : log.caller
 
     line += `${line === '' ? '' : ' '}<${prettyCaller}>`
diff --git a/lib/utils/prettify-metadata.test.js b/lib/utils/prettify-metadata.test.js
index cf2f892c..a95a8c9c 100644
--- a/lib/utils/prettify-metadata.test.js
+++ b/lib/utils/prettify-metadata.test.js
@@ -4,7 +4,7 @@ const tap = require('tap')
 const prettifyMetadata = require('./prettify-metadata')
 const getColorizer = require('../colors')
 const context = {
-  customPrettifiers: {},
+  customPrettifiers: new Map(),
   colorizer: {
     colors: {}
   }
@@ -91,20 +91,19 @@ tap.test('works with all four present', async t => {
 })
 
 tap.test('uses prettifiers from passed prettifiers object', async t => {
-  const prettifiers = {
-    name (input) {
-      return input.toUpperCase()
-    },
-    pid (input) {
-      return input + '__'
-    },
-    hostname (input) {
-      return input.toUpperCase()
-    },
-    caller (input) {
-      return input.toUpperCase()
-    }
-  }
+  const prettifiers = new Map()
+  prettifiers.set('name', (input) => {
+    return input.toUpperCase()
+  })
+  prettifiers.set('pid', (input) => {
+    return input + '__'
+  })
+  prettifiers.set('hostname', (input) => {
+    return input.toUpperCase()
+  })
+  prettifiers.set('caller', (input) => {
+    return input.toUpperCase()
+  })
   const str = prettifyMetadata({
     log: { pid: '1234', hostname: 'bar', caller: 'baz', name: 'joe' },
     context: {
@@ -116,20 +115,19 @@ tap.test('uses prettifiers from passed prettifiers object', async t => {
 })
 
 tap.test('uses colorizer from passed context to colorize metadata', async t => {
-  const prettifiers = {
-    name (input, _key, _log, { colors }) {
-      return colors.blue(input)
-    },
-    pid (input, _key, _log, { colors }) {
-      return colors.red(input)
-    },
-    hostname (input, _key, _log, { colors }) {
-      return colors.green(input)
-    },
-    caller (input, _key, _log, { colors }) {
-      return colors.cyan(input)
-    }
-  }
+  const prettifiers = new Map()
+  prettifiers.set('name', (input, _key, _log, { colors }) => {
+    return colors.blue(input)
+  })
+  prettifiers.set('pid', (input, _key, _log, { colors }) => {
+    return colors.red(input)
+  })
+  prettifiers.set('hostname', (input, _key, _log, { colors }) => {
+    return colors.green(input)
+  })
+  prettifiers.set('caller', (input, _key, _log, { colors }) => {
+    return colors.cyan(input)
+  })
   const log = { name: 'foo', pid: '1234', hostname: 'bar', caller: 'baz' }
   const colorizer = getColorizer(true)
   const context = {
diff --git a/lib/utils/prettify-object.js b/lib/utils/prettify-object.js
index 5de0f5cb..5f1ecea5 100644
--- a/lib/utils/prettify-object.js
+++ b/lib/utils/prettify-object.js
@@ -57,8 +57,8 @@ function prettifyObject ({
   const { plain, errors } = Object.entries(log).reduce(({ plain, errors }, [k, v]) => {
     if (keysToIgnore.includes(k) === false) {
       // Pre-apply custom prettifiers, because all 3 cases below will need this
-      const pretty = typeof customPrettifiers[k] === 'function'
-        ? customPrettifiers[k](v, k, log, { colors: colorizer.colors })
+      const pretty = typeof customPrettifiers.get(k) === 'function'
+        ? customPrettifiers.get(k)(v, k, log, { colors: colorizer.colors })
         : v
       if (errorLikeKeys.includes(k)) {
         errors[k] = pretty
@@ -82,7 +82,7 @@ function prettifyObject ({
     // Put each object entry on its own line
     Object.entries(plain).forEach(([keyName, keyValue]) => {
       // custom prettifiers are already applied above, so we can skip it now
-      let lines = typeof customPrettifiers[keyName] === 'function'
+      let lines = typeof customPrettifiers.get(keyName) === 'function'
         ? keyValue
         : stringifySafe(keyValue, null, 2)
 
@@ -99,7 +99,7 @@ function prettifyObject ({
   // Errors
   Object.entries(errors).forEach(([keyName, keyValue]) => {
     // custom prettifiers are already applied above, so we can skip it now
-    const lines = typeof customPrettifiers[keyName] === 'function'
+    const lines = typeof customPrettifiers.get(keyName) === 'function'
       ? keyValue
       : stringifySafe(keyValue, null, 2)
 
diff --git a/lib/utils/prettify-object.test.js b/lib/utils/prettify-object.test.js
index 2dde4a9a..a3ea87b8 100644
--- a/lib/utils/prettify-object.test.js
+++ b/lib/utils/prettify-object.test.js
@@ -11,7 +11,7 @@ const getColorizer = require('../colors')
 const context = {
   EOL: '\n',
   IDENT: '    ',
-  customPrettifiers: {},
+  customPrettifiers: new Map(),
   errorLikeObjectKeys: ERROR_LIKE_KEYS,
   objectColorizer: colors(),
   singleLine: false,
@@ -76,9 +76,9 @@ tap.test('works with error props', async t => {
 })
 
 tap.test('customPrettifiers gets applied', async t => {
-  const customPrettifiers = {
-    foo: v => v.toUpperCase()
-  }
+  const customPrettifiers = new Map([
+    ['foo', v => v.toUpperCase()]
+  ])
   const str = prettifyObject({
     log: { foo: 'foo' },
     context: {
@@ -90,9 +90,9 @@ tap.test('customPrettifiers gets applied', async t => {
 })
 
 tap.test('skips lines omitted by customPrettifiers', async t => {
-  const customPrettifiers = {
-    foo: () => { return undefined }
-  }
+  const customPrettifiers = new Map([
+    ['foo', () => { return undefined }]
+  ])
   const str = prettifyObject({
     log: { foo: 'foo', bar: 'bar' },
     context: {
@@ -110,9 +110,9 @@ tap.test('joined lines omits starting eol', async t => {
     context: {
       ...context,
       IDENT: '',
-      customPrettifiers: {
-        calls: val => '\n' + val.map(it => '  ' + it).join('\n')
-      }
+      customPrettifiers: new Map([
+        ['calls', val => '\n' + val.map(it => '  ' + it).join('\n')]
+      ])
     }
   })
   t.equal(str, [
@@ -126,9 +126,9 @@ tap.test('joined lines omits starting eol', async t => {
 })
 
 tap.test('errors skips prettifiers', async t => {
-  const customPrettifiers = {
-    err: () => { return 'is_err' }
-  }
+  const customPrettifiers = new Map([
+    ['err', () => { return 'is_err' }]
+  ])
   const str = prettifyObject({
     log: { err: Error('boom') },
     context: {
@@ -140,9 +140,9 @@ tap.test('errors skips prettifiers', async t => {
 })
 
 tap.test('errors skips prettifying if no lines are present', async t => {
-  const customPrettifiers = {
-    err: () => { return undefined }
-  }
+  const customPrettifiers = new Map([
+    ['err', () => { return undefined }]
+  ])
   const str = prettifyObject({
     log: { err: Error('boom') },
     context: {
diff --git a/lib/utils/prettify-time.js b/lib/utils/prettify-time.js
index e876b35f..6f4fa95a 100644
--- a/lib/utils/prettify-time.js
+++ b/lib/utils/prettify-time.js
@@ -26,7 +26,7 @@ function prettifyTime ({ log, context }) {
     timestampKey,
     translateTime: translateFormat
   } = context
-  const prettifier = context.customPrettifiers?.time
+  const prettifier = context.customPrettifiers?.get('time')
   let time = null
 
   if (timestampKey in log) {
diff --git a/lib/utils/prettify-time.test.js b/lib/utils/prettify-time.test.js
index cfde6627..44ec8ebb 100644
--- a/lib/utils/prettify-time.test.js
+++ b/lib/utils/prettify-time.test.js
@@ -10,7 +10,7 @@ const {
 const context = {
   timestampKey: TIMESTAMP_KEY,
   translateTime: true,
-  customPrettifiers: {}
+  customPrettifiers: new Map()
 }
 
 tap.test('returns `undefined` if `time` or `timestamp` not in log', async t => {
@@ -216,11 +216,9 @@ tap.test('uses custom prettifier', async t => {
     log: { time: 0 },
     context: {
       ...context,
-      customPrettifiers: {
-        time () {
-          return 'done'
-        }
-      }
+      customPrettifiers: new Map([
+        ['time', () => { return 'done' }]
+      ])
     }
   })
   t.equal(str, 'done')
diff --git a/test/basic.test.js b/test/basic.test.js
index e2a58304..107ddb09 100644
--- a/test/basic.test.js
+++ b/test/basic.test.js
@@ -240,9 +240,9 @@ test('basic prettifier tests', (t) => {
       30: 'ok',
       40: 'not great'
     }
-    const customPrettifiers = {
-      level: (level) => `LEVEL: ${veryCustomLevels[level]}`
-    }
+    const customPrettifiers = new Map([
+      ['level', (level) => `LEVEL: ${veryCustomLevels[level]}`]
+    ])
     const pretty = prettyFactory({ customPrettifiers })
     const log = pino({}, new Writable({
       write (chunk, enc, cb) {
@@ -259,9 +259,9 @@ test('basic prettifier tests', (t) => {
 
   t.test('can use a customPrettifier on different-level-key output', (t) => {
     t.plan(1)
-    const customPrettifiers = {
-      level: (level) => `LEVEL: ${level.toUpperCase()}`
-    }
+    const customPrettifiers = new Map([
+      ['level', (level) => `LEVEL: ${level.toUpperCase()}`]
+    ])
     const pretty = prettyFactory({ levelKey: 'bar', customPrettifiers })
     const log = pino({}, new Writable({
       write (chunk, enc, cb) {
@@ -278,11 +278,14 @@ test('basic prettifier tests', (t) => {
 
   t.test('can use a customPrettifier to get final level label (no color)', (t) => {
     t.plan(1)
-    const customPrettifiers = {
-      level: (level, key, logThis, { label }) => {
-        return `LEVEL: ${label}`
-      }
-    }
+    const customPrettifiers = new Map([
+      [
+        'level',
+        (level, key, logThis, { label }) => {
+          return `LEVEL: ${label}`
+        }
+      ]
+    ])
     const pretty = prettyFactory({ customPrettifiers, colorize: false, useOnlyCustomProps: false })
     const log = pino({}, new Writable({
       write (chunk, enc, cb) {
@@ -299,11 +302,14 @@ test('basic prettifier tests', (t) => {
 
   t.test('can use a customPrettifier to get final level label (colorized)', (t) => {
     t.plan(1)
-    const customPrettifiers = {
-      level: (level, key, logThis, { label, labelColorized }) => {
-        return `LEVEL: ${labelColorized}`
-      }
-    }
+    const customPrettifiers = new Map([
+      [
+        'level',
+        (level, key, logThis, { label, labelColorized }) => {
+          return `LEVEL: ${labelColorized}`
+        }
+      ]
+    ])
     const pretty = prettyFactory({ customPrettifiers, colorize: true, useOnlyCustomProps: false })
     const log = pino({}, new Writable({
       write (chunk, enc, cb) {
@@ -320,9 +326,9 @@ test('basic prettifier tests', (t) => {
 
   t.test('can use a customPrettifier on name output', (t) => {
     t.plan(1)
-    const customPrettifiers = {
-      name: (hostname) => `NAME: ${hostname}`
-    }
+    const customPrettifiers = new Map([
+      ['name', (hostname) => `NAME: ${hostname}`]
+    ])
     const pretty = prettyFactory({ customPrettifiers })
     const log = pino({}, new Writable({
       write (chunk, enc, cb) {
@@ -340,10 +346,10 @@ test('basic prettifier tests', (t) => {
 
   t.test('can use a customPrettifier on hostname and pid output', (t) => {
     t.plan(1)
-    const customPrettifiers = {
-      hostname: (hostname) => `HOSTNAME: ${hostname}`,
-      pid: (pid) => `PID: ${pid}`
-    }
+    const customPrettifiers = new Map([
+      ['hostname', (hostname) => `HOSTNAME: ${hostname}`],
+      ['pid', (pid) => `PID: ${pid}`]
+    ])
     const pretty = prettyFactory({ customPrettifiers, ignore: '' })
     const log = pino({}, new Writable({
       write (chunk, enc, cb) {
@@ -360,9 +366,9 @@ test('basic prettifier tests', (t) => {
 
   t.test('can use a customPrettifier on default time output', (t) => {
     t.plan(1)
-    const customPrettifiers = {
-      time: (timestamp) => `TIME: ${timestamp}`
-    }
+    const customPrettifiers = new Map([
+      ['time', (timestamp) => `TIME: ${timestamp}`]
+    ])
     const pretty = prettyFactory({ customPrettifiers })
     const log = pino({}, new Writable({
       write (chunk, enc, cb) {
@@ -379,9 +385,9 @@ test('basic prettifier tests', (t) => {
 
   t.test('can use a customPrettifier on the caller', (t) => {
     t.plan(1)
-    const customPrettifiers = {
-      caller: (caller) => `CALLER: ${caller}`
-    }
+    const customPrettifiers = new Map([
+      ['caller', (caller) => `CALLER: ${caller}`]
+    ])
     const pretty = prettyFactory({ customPrettifiers })
     const log = pino({}, new Writable({
       write (chunk, enc, cb) {
@@ -398,9 +404,9 @@ test('basic prettifier tests', (t) => {
 
   t.test('can use a customPrettifier on translateTime-time output', (t) => {
     t.plan(1)
-    const customPrettifiers = {
-      time: (timestamp) => `TIME: ${timestamp}`
-    }
+    const customPrettifiers = new Map([
+      ['time', (timestamp) => `TIME: ${timestamp}`]
+    ])
     const pretty = prettyFactory({ customPrettifiers, translateTime: true })
     const log = pino({}, new Writable({
       write (chunk, enc, cb) {
@@ -824,10 +830,10 @@ test('basic prettifier tests', (t) => {
   t.test('prettifies custom key', (t) => {
     t.plan(1)
     const pretty = prettyFactory({
-      customPrettifiers: {
-        foo: val => `${val}_baz\nmultiline`,
-        cow: val => val.toUpperCase()
-      }
+      customPrettifiers: new Map([
+        ['foo', val => `${val}_baz\nmultiline`],
+        ['cow', val => val.toUpperCase()]
+      ])
     })
     const arst = pretty('{"msg":"hello world", "foo": "bar", "cow": "moo", "level":30}')
     t.equal(arst, 'INFO: hello world\n    foo: bar_baz\n    multiline\n    cow: MOO\n')
@@ -836,9 +842,9 @@ test('basic prettifier tests', (t) => {
   t.test('does not add trailing space if prettified value begins with eol', (t) => {
     t.plan(1)
     const pretty = prettyFactory({
-      customPrettifiers: {
-        calls: val => '\n' + val.map(it => '  ' + it).join('\n')
-      }
+      customPrettifiers: new Map([
+        ['calls', val => '\n' + val.map(it => '  ' + it).join('\n')]
+      ])
     })
     const arst = pretty('{"msg":"doing work","calls":["step 1","step 2","step 3"],"level":30}')
     t.equal(arst, 'INFO: doing work\n    calls:\n      step 1\n      step 2\n      step 3\n')
@@ -847,10 +853,10 @@ test('basic prettifier tests', (t) => {
   t.test('does not prettify custom key that does not exists', (t) => {
     t.plan(1)
     const pretty = prettyFactory({
-      customPrettifiers: {
-        foo: val => `${val}_baz`,
-        cow: val => val.toUpperCase()
-      }
+      customPrettifiers: new Map([
+        ['foo', val => `${val}_baz`],
+        ['cow', val => val.toUpperCase()]
+      ])
     })
     const arst = pretty('{"msg":"hello world", "foo": "bar", "level":30}')
     t.equal(arst, 'INFO: hello world\n    foo: bar_baz\n')
@@ -1054,10 +1060,10 @@ test('basic prettifier tests', (t) => {
     const pretty = prettyFactory({
       singleLine: true,
       colorize: false,
-      customPrettifiers: {
-        upper: val => val.toUpperCase(),
-        undef: () => undefined
-      }
+      customPrettifiers: new Map([
+        ['upper', val => val.toUpperCase()],
+        ['undef', () => undefined]
+      ])
     })
     const log = pino({}, new Writable({
       write (chunk, enc, cb) {
@@ -1159,10 +1165,10 @@ test('basic prettifier tests', (t) => {
       mkdir: true,
       append: false,
       destination: new SonicBoom({ dest: destination, async: false, mkdir: true, append: true }),
-      customPrettifiers: {
-        upper: val => val.toUpperCase(),
-        undef: () => undefined
-      }
+      customPrettifiers: new Map([
+        ['upper', val => val.toUpperCase()],
+        ['undef', () => undefined]
+      ])
     })
     const log = pino(pretty)
     log.info({ msg: 'message', extra: { foo: 'bar', number: 42 }, upper: 'foobar', undef: 'this will not show up' })
diff --git a/test/error-objects.test.js b/test/error-objects.test.js
index b9840c6c..653f3a47 100644
--- a/test/error-objects.test.js
+++ b/test/error-objects.test.js
@@ -151,9 +151,9 @@ test('error like objects tests', (t) => {
     t.plan(4)
     const pretty = prettyFactory({
       errorLikeObjectKeys: ['err'],
-      customPrettifiers: {
-        err: val => `error is ${val.message}`
-      }
+      customPrettifiers: new Map([
+        ['err', val => `error is ${val.message}`]
+      ])
     })
 
     const err = Error('hello world')
diff --git a/test/types/pino-pretty.test-d.ts b/test/types/pino-pretty.test-d.ts
index 8649edc3..bd64570d 100644
--- a/test/types/pino-pretty.test-d.ts
+++ b/test/types/pino-pretty.test-d.ts
@@ -4,6 +4,7 @@ import pretty from "../../";
 import PinoPretty, {
   PinoPretty as PinoPrettyNamed,
   PrettyOptions,
+  CustomPrettifiers,
   colorizerFactory,
   prettyFactory
 } from "../../";
@@ -13,6 +14,19 @@ import PinoPrettyCjsImport = require("../../");
 import PrettyStream = PinoPretty.PrettyStream;
 const PinoPrettyCjs = require("../../");
 
+const customPrettifiers: CustomPrettifiers = new Map();
+customPrettifiers.set("key", (value) => {
+  return value.toString().toUpperCase();
+});
+customPrettifiers.set(
+  "level",
+  (level, levelKey, log, { label, labelColorized, colors }) => {
+    return level.toString();
+  },
+);
+customPrettifiers.set("foo", (value, key, log, { colors }) => {
+  return value.toString();
+});
 const options: PinoPretty.PrettyOptions = {
   colorize: true,
   crlf: false,
@@ -29,17 +43,7 @@ const options: PinoPretty.PrettyOptions = {
   minimumLevel: "trace",
   translateTime: "UTC:h:MM:ss TT Z",
   singleLine: false,
-  customPrettifiers: {
-    key: (value) => {
-      return value.toString().toUpperCase();
-    },
-    level: (level, levelKey, log, { label, labelColorized, colors }) => {
-      return level.toString();
-    },
-    foo: (value, key, log, { colors }) => {
-      return value.toString();
-    }
-  },
+  customPrettifiers,
   customLevels: 'verbose:5',
   customColors: 'default:white,verbose:gray',
   sync: false,