diff --git a/src/duration-format-ponyfill.ts b/src/duration-format-ponyfill.ts
index 15ccd7d..685dd57 100644
--- a/src/duration-format-ponyfill.ts
+++ b/src/duration-format-ponyfill.ts
@@ -110,7 +110,11 @@ export default class DurationFormat {
           : unitStyle === 'numeric'
           ? {}
           : {style: 'unit', unit: nfUnit, unitDisplay: unitStyle}
-      list.push(new Intl.NumberFormat(locale, nfOpts).format(value))
+      list.push(
+        nfUnit === 'month' && unitStyle === 'narrow'
+          ? `${value}mo`
+          : new Intl.NumberFormat(locale, nfOpts).format(value),
+      )
     }
     return new ListFormat(locale, {
       type: 'unit',
diff --git a/test/relative-time.js b/test/relative-time.js
index de5c102..f209cdc 100644
--- a/test/relative-time.js
+++ b/test/relative-time.js
@@ -532,6 +532,17 @@ suite('relative-time', function () {
       assert.equal(time.shadowRoot.textContent, '10y')
     })
 
+    test('micro formats months', async () => {
+      const datetime = new Date()
+      datetime.setMonth(datetime.getMonth() - 2)
+      const time = document.createElement('relative-time')
+      time.setAttribute('tense', 'past')
+      time.setAttribute('datetime', datetime)
+      time.setAttribute('format', 'micro')
+      await Promise.resolve()
+      assert.equal(time.shadowRoot.textContent, '2mo')
+    })
+
     test('micro formats future times', async () => {
       const now = new Date(Date.now() + 3 * 1000).toISOString()
       const time = document.createElement('relative-time')
@@ -1941,7 +1952,7 @@ suite('relative-time', function () {
         datetime: '2022-09-24T14:46:00.000Z',
         tense: 'future',
         format: 'micro',
-        expected: '1m',
+        expected: '1mo',
       },
       {
         datetime: '2022-10-23T14:46:00.000Z',
@@ -1991,7 +2002,7 @@ suite('relative-time', function () {
         datetime: '2022-11-24T14:46:00.000Z',
         tense: 'future',
         format: 'micro',
-        expected: '1m',
+        expected: '1mo',
       },
       {
         datetime: '2023-10-23T14:46:00.000Z',
@@ -2023,7 +2034,7 @@ suite('relative-time', function () {
         datetime: '2022-11-24T14:46:00.000Z',
         tense: 'past',
         format: 'micro',
-        expected: '1m',
+        expected: '1mo',
       },
       {
         datetime: '2022-10-25T14:46:00.000Z',
@@ -2073,7 +2084,7 @@ suite('relative-time', function () {
         datetime: '2022-09-23T14:46:00.000Z',
         tense: 'past',
         format: 'micro',
-        expected: '1m',
+        expected: '1mo',
       },
       {
         datetime: '2021-10-25T14:46:00.000Z',
@@ -2178,13 +2189,13 @@ suite('relative-time', function () {
       {
         datetime: '2021-10-30T14:46:00.000Z',
         format: 'elapsed',
-        expected: '11m 29d',
+        expected: '11mo 29d',
       },
       {
         datetime: '2021-10-30T14:46:00.000Z',
         format: 'elapsed',
         precision: 'month',
-        expected: '11m',
+        expected: '11mo',
       },
       {
         datetime: '2021-10-29T14:46:00.000Z',