diff --git a/package.json b/package.json
index 06d9451..acbf77a 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,6 @@
     "@hapi/boom": "^9.1.0",
     "boolean": "3.0.1",
     "country-language": "^0.1.7",
-    "dayjs": "^1.8.30",
     "debug": "^4.1.1",
     "i18n": "^0.9.1",
     "i18n-locales": "^0.0.4",
@@ -60,7 +59,7 @@
     "xo": "0.25"
   },
   "engines": {
-    "node": ">=6.4.0"
+    "node": ">=7.0.0"
   },
   "files": [
     "lib",
diff --git a/src/index.js b/src/index.js
index 889baf9..710bb30 100644
--- a/src/index.js
+++ b/src/index.js
@@ -4,7 +4,6 @@ const Boom = require('@hapi/boom');
 const debug = require('debug')('ladjs:i18n');
 const i18n = require('i18n');
 const locales = require('i18n-locales');
-const dayjs = require('dayjs');
 const multimatch = require('multimatch');
 const titleize = require('titleize');
 const tlds = require('tlds');
@@ -27,11 +26,9 @@ class I18N {
         cookie: 'locale',
         cookieOptions: {
           // Disable signed cookies in NODE_ENV=test
-          signed: process.env.NODE_ENV !== 'test',
-          expires: dayjs()
-            .add(1, 'year')
-            .toDate()
+          signed: process.env.NODE_ENV !== 'test'
         },
+        expiryMs: 31556952000, // one year in ms
         indent: '  ',
         defaultLocale: 'en',
         syncFiles: boolean(process.env.I18N_SYNC_FILES || true),
@@ -71,6 +68,12 @@ class I18N {
         `Default locale of ${this.config.defaultLocale} must be included in list of locales`
       );
 
+    // make sure expires is not set in cookieOptions
+    if (this.config.cookieOptions.expires)
+      throw new Error(
+        'Please specify expiryMs config option instead of passing a Date to cookieOptions config'
+      );
+
     // inherit i18n object
     Object.assign(this, i18n);
 
@@ -274,7 +277,10 @@ class I18N {
     debug('found valid language "%s"', locale);
 
     // set the cookie for future requests
-    ctx.cookies.set(this.config.cookie, locale, this.config.cookieOptions);
+    ctx.cookies.set(this.config.cookie, locale, {
+      ...this.config.cookieOptions,
+      expires: new Date(Date.now() + this.config.expiryMs)
+    });
     debug('set cookies for locale "%s"', locale);
 
     // if the user is logged in and ctx.isAuthenticated() exists,
diff --git a/test/test.js b/test/test.js
index 6c00756..c20f4ab 100644
--- a/test/test.js
+++ b/test/test.js
@@ -628,3 +628,10 @@ test('redirects sets users last_locale', async t => {
   t.is(res.status, 200);
   t.is(res.body.last_locale, 'en');
 });
+
+test('errors if cookieOptions.expires is set', t => {
+  t.throws(() => new I18N({ cookieOptions: { expires: new Date() } }), {
+    message:
+      'Please specify expiryMs config option instead of passing a Date to cookieOptions config'
+  });
+});
diff --git a/yarn.lock b/yarn.lock
index 9d34205..a9f6a49 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2295,11 +2295,6 @@ date-time@^2.1.0:
   dependencies:
     time-zone "^1.0.0"
 
-dayjs@^1.8.30:
-  version "1.8.30"
-  resolved "https://registry.yarnpkg.com/dayjs/-/dayjs-1.8.30.tgz#d3b314d3ccdc179015d915fd3c6e14422c026378"
-  integrity sha512-5s5IGuP5bVvIbOWkEDcfmXsUj24fZW1NMHVVSdSFF/kW8d+alZcI9SpBKC+baEyBe+z3fUp17y75ulstv5swUw==
-
 debug@*, debug@4, debug@^4.0.0, debug@^4.0.1, debug@^4.1.0, debug@^4.1.1:
   version "4.1.1"
   resolved "https://registry.yarnpkg.com/debug/-/debug-4.1.1.tgz#3b72260255109c6b589cee050f1d516139664791"