diff --git a/test/relative-time.js b/test/relative-time.js
index 10a507c..1f20571 100644
--- a/test/relative-time.js
+++ b/test/relative-time.js
@@ -475,13 +475,14 @@ suite('relative-time', function () {
     })
 
     test('micro formats years', async () => {
-      const now = new Date(Date.now() - 10 * 365 * 24 * 60 * 60 * 1000).toISOString()
+      const datetime = new Date()
+      datetime.setFullYear(datetime.getFullYear() - 10)
       const time = document.createElement('relative-time')
       time.setAttribute('tense', 'past')
-      time.setAttribute('datetime', now)
+      time.setAttribute('datetime', datetime)
       time.setAttribute('format', 'micro')
       await Promise.resolve()
-      assert.equal(time.shadowRoot.textContent, '11y')
+      assert.equal(time.shadowRoot.textContent, '10y')
     })
 
     test('micro formats future times', async () => {