diff --git a/lib/deep-map.js b/lib/deep-map.js
index c14857c..26727ee 100644
--- a/lib/deep-map.js
+++ b/lib/deep-map.js
@@ -38,12 +38,18 @@ const deepMap = (input, handler = v => v, path = ['$'], seen = new Set([input]))
   } else if (typeof input === 'object' || typeof input === 'function') {
     const result = {}
 
-    for (const propertyName of Object.getOwnPropertyNames(input)) {
-    // skip logging internal properties
-      if (propertyName.startsWith('_')) {
-        continue
+    const publicPropertyNames = Object.getOwnPropertyNames(input).filter((name) => !name.startsWith('_'))
+
+    // if there are no public properties, check for custom serialization
+    if (publicPropertyNames.length === 0 && typeof input.toJSON === 'function') {
+      try {
+        return handler(input.toJSON(), path)
+      } catch (err) {
+        return `[error getting JSON value: ${err.message}]`
       }
+    }
 
+    for (const propertyName of publicPropertyNames) {
       try {
         const property = input[propertyName]
         const propertyPath = [...path, propertyName]
diff --git a/tap-snapshots/test/suite/server-redact-nonstring.test.cjs b/tap-snapshots/test/suite/server-redact-nonstring.test.cjs
index 314bf23..4660761 100644
--- a/tap-snapshots/test/suite/server-redact-nonstring.test.cjs
+++ b/tap-snapshots/test/suite/server-redact-nonstring.test.cjs
@@ -29,6 +29,10 @@ exports[`test/suite.js TAP server redact nonstring nonString emptyObject just se
 Object {}
 `
 
+exports[`test/suite.js TAP server redact nonstring nonString exampleCustomSerializerThrows just serverRedact > must match snapshot 1`] = `
+[error getting JSON value: Error in toJSON]
+`
+
 exports[`test/suite.js TAP server redact nonstring nonString exampleGetterThrows just serverRedact > must match snapshot 1`] = `
 Object {
   "getter": "[error getting value: Error in getter]",
@@ -148,6 +152,10 @@ Object {
 }
 `
 
+exports[`test/suite.js TAP server redact nonstring nonStringSensitve exampleCustomSerializer just serverRedact > must match snapshot 1`] = `
+latitude: 37.7822689; longitude: -122.3937449; secret: [REDACTED_NPM_SECRET]
+`
+
 exports[`test/suite.js TAP server redact nonstring nonStringSensitve exampleGetter just serverRedact > must match snapshot 1`] = `
 Object {
   "getter": "[REDACTED_NPM_SECRET]",
diff --git a/test/fixtures/complex.js b/test/fixtures/complex.js
index 0090210..7b15ecf 100644
--- a/test/fixtures/complex.js
+++ b/test/fixtures/complex.js
@@ -27,6 +27,15 @@ const exampleGetter = (() => {
   return example
 })()
 
+const exampleCustomSerializer = (() => {
+  class ExampleClass {
+    toJSON () {
+      return `latitude: 37.7822689; longitude: -122.3937449; secret: ${examples.NPM_SECRET.npm_36}`
+    }
+  }
+  return new ExampleClass()
+})()
+
 const exampleGetterThrows = (() => {
   const example = {}
   Object.defineProperty(example, 'getter', {
@@ -37,6 +46,15 @@ const exampleGetterThrows = (() => {
   return example
 })()
 
+const exampleCustomSerializerThrows = (() => {
+  class ExampleClass {
+    toJSON () {
+      throw new Error('Error in toJSON')
+    }
+  }
+  return new ExampleClass()
+})()
+
 const circular = (() => {
   const example = exampleObject
   exampleObject.nested = exampleObject
@@ -64,6 +82,7 @@ const examplesNonString = {
   objectNumbers: { a: 1, b: 2, c: 3 },
   objectStrings: { a: 'a', b: 'b', c: 'c' },
   exampleGetterThrows,
+  exampleCustomSerializerThrows,
 }
 
 const error = (() => {
@@ -81,6 +100,7 @@ const examplesNonStringSensitive = {
   circular,
   circularArray,
   exampleGetter,
+  exampleCustomSerializer,
   error,
   privateProperty: {
     ...exampleObject,
diff --git a/test/utils.js b/test/utils.js
index a439a0d..daa77ce 100644
--- a/test/utils.js
+++ b/test/utils.js
@@ -119,6 +119,30 @@ t.test('error with buffer', async () => {
 
 t.same(deepMap(new TextEncoder().encode('hello')), '[unable to log instanceof Uint8Array]')
 
+t.test('deepMap date', async (t) => {
+  const date = new Date('2010-01-12T00:00:00.000Z')
+  const result = deepMap(date)
+  t.same(result, '2010-01-12T00:00:00.000Z')
+})
+
+t.test('deepMap nested date', async (t) => {
+  const date = new Date('2010-01-12T00:00:00.000Z')
+  const result = deepMap({ message: 'npm version 0.0.1 published', date })
+  t.same(result, ({ message: 'npm version 0.0.1 published', date: '2010-01-12T00:00:00.000Z' }))
+})
+
+t.test('deepMap URL', async (t) => {
+  const url = new URL('https://www.npmjs.com/package/@npmcli/redact?activeTab=versions')
+  const result = deepMap(url)
+  t.same(result, 'https://www.npmjs.com/package/@npmcli/redact?activeTab=versions')
+})
+
+t.test('deepMap nested URL', async (t) => {
+  const url = new URL('https://www.npmjs.com/package/@npmcli/redact?activeTab=versions')
+  const result = deepMap({ message: 'request start', url })
+  t.same(result, ({ message: 'request start', url: 'https://www.npmjs.com/package/@npmcli/redact?activeTab=versions' }))
+})
+
 const redactUrl = redactMatchers(
   redactUrlMatcher(
     redactUrlHostnameMatcher({ hostname: 'example.com', replacement: 'example.net' }),