diff --git a/lib/serializer.js b/lib/serializer.js
index 1b3a77d8..acd3cdc4 100644
--- a/lib/serializer.js
+++ b/lib/serializer.js
@@ -108,7 +108,7 @@ module.exports = class Serializer {
   asDate (date) {
     if (date === null) return '""'
     if (date instanceof Date) {
-      return '"' + new Date(date.getTime() - (date.getTimezoneOffset() * 60000)).toISOString().slice(0, 10) + '"'
+      return '"' + new Date(date.getTime() - (date.getTimezoneOffset() * 60000)).toISOString().slice(0, -14) + '"'
     }
     if (typeof date === 'string') {
       return asString(date)
@@ -119,7 +119,7 @@ module.exports = class Serializer {
   asTime (date) {
     if (date === null) return '""'
     if (date instanceof Date) {
-      return '"' + new Date(date.getTime() - (date.getTimezoneOffset() * 60000)).toISOString().slice(11, 19) + '"'
+      return '"' + new Date(date.getTime() - (date.getTimezoneOffset() * 60000)).toISOString().slice(-13, -5) + '"'
     }
     if (typeof date === 'string') {
       return asString(date)
diff --git a/test/date.test.js b/test/date.test.js
index 79f21b3d..baf874e4 100644
--- a/test/date.test.js
+++ b/test/date.test.js
@@ -6,6 +6,18 @@ const build = require('..')
 
 process.env.TZ = 'UTC'
 
+for (const iso of ['+010000-02-03T04:05:06.000Z', '-000001-02-03T04:05:06.000Z', '0000-02-03T04:05:06.000Z', '9999-02-03T04:05:06.000Z']) {
+  test(`preserve the whole calendar date for ${iso}`, (t) => {
+    const stringify = build({ type: 'string', format: 'date' })
+    t.assert.equal(stringify(new Date(iso)), JSON.stringify(iso.split('T')[0]))
+  })
+
+  test(`preserve the time for ${iso}`, (t) => {
+    const stringify = build({ type: 'string', format: 'time' })
+    t.assert.equal(stringify(new Date(iso)), '"04:05:06"')
+  })
+}
+
 test('render a date in a string as JSON', (t) => {
   t.plan(2)