diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index f5dc344..20ee438 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,14 +1,18 @@
 name: Node CI
 
-on: [push]
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
 
 jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Use Node.js 18.x
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v3
       with:
         node-version: 18.x
     - name: npm install, build, and test
diff --git a/README.md b/README.md
index bc5ca8d..34bbe20 100644
--- a/README.md
+++ b/README.md
@@ -65,7 +65,7 @@ So, a relative date phrase is used for up to a month and then the actual date is
 | Property Name  | Attribute Name   | Possible Values                                                                             | Default Value                    |
 |:---------------|:-----------------|:--------------------------------------------------------------------------------------------|:---------------------------------|
 | `datetime`     | `datetime`       | `string`                                                                                    | -                                |
-| `format`       | `format`         | `'datetime'\|'relative'\|'duration'`                                                        | `'auto'`                           |
+| `format`       | `format`         | `'datetime'\|'relative'\|'duration'`                                                        | `'auto'`                         |
 | `date`         | -                | `Date \| null`                                                                              | -                                |
 | `tense`        | `tense`          | `'auto'\|'past'\|'future'`                                                                  | `'auto'`                         |
 | `precision`    | `precision`      | `'year'\|'month'\|'day'\|'hour'\|'minute'\|'second'`                                        | `'second'`                       |
@@ -83,7 +83,7 @@ So, a relative date phrase is used for up to a month and then the actual date is
 
 <sup>*</sup>: If unspecified, `formatStyle` will return `'narrow'` if `format` is `'elapsed'` or `'micro'`, `'short'` if the format is `'relative'` or `'datetime'`, otherwise it will be `'long'`.
 
-<sup>**</sup>: If unspecified, `month` will return the same value as `formatStyle` whenever `format` is `'datetime'`, otherwise it wil be `'short'`.
+<sup>**</sup>: If unspecified, `month` will return the same value as `formatStyle` whenever `format` is `'datetime'`, otherwise it will be `'short'`.
 
 <sup>***</sup>: If unspecified, `weekday` will return the same value as `formatStyle` whenever `format` is `'datetime'`, otherwise it will be `undefined`.
 
@@ -122,7 +122,7 @@ Unless specified, it will consider `weekday` to be `'long'`, `month` to be `'lon
 
 ###### `format=relative`
 
-The default `relative` format will display dates relative to the current time (unless they are past the `threshold` value - see below). The values are rounded to display a single unit, for example if the time between the given `datetime` and the current wall clock time exceeds a day, then the format will _only_ ouput in days, and will not display hours, minutes or seconds. Some examples of this format with the default options and an `en` locale:
+The default `relative` format will display dates relative to the current time (unless they are past the `threshold` value - see below). The values are rounded to display a single unit, for example if the time between the given `datetime` and the current wall clock time exceeds a day, then the format will _only_ output in days, and will not display hours, minutes or seconds. Some examples of this format with the default options and an `en` locale:
 
  - `in 20 days`
  - `20 days ago`
@@ -146,7 +146,7 @@ This is similar to the `format=duration`, except the `formatStyle` defaults to `
 
 ###### `format=auto`
 
-This is identical to `format=relative`. Code that uses `format=auto` should migrae to `format=relative` as this will be the new default in a later version.
+This is identical to `format=relative`. Code that uses `format=auto` should migrate to `format=relative` as this will be the new default in a later version.
 
 ###### `format=micro`
 
diff --git a/package-lock.json b/package-lock.json
index 1f1b311..7c40a12 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -6753,9 +6753,9 @@
       }
     },
     "node_modules/word-wrap": {
-      "version": "1.2.3",
-      "resolved": "https://registry.npmjs.org/word-wrap/-/word-wrap-1.2.3.tgz",
-      "integrity": "sha512-Hz/mrNwitNRh/HUAtM/VT/5VH+ygD6DV7mYKZAtHOrbs8U7lvPS6xf7EJKMF0uW1KJCl0H701g3ZGus+muE5vQ==",
+      "version": "1.2.4",
+      "resolved": "https://registry.npmjs.org/word-wrap/-/word-wrap-1.2.4.tgz",
+      "integrity": "sha512-2V81OA4ugVo5pRo46hAoD2ivUJx8jXmWXfUkY4KFNw0hEptvN0QfH3K4nHiwzGeKl5rFKedV48QVoqYavy4YpA==",
       "dev": true,
       "engines": {
         "node": ">=0.10.0"
@@ -11874,9 +11874,9 @@
       }
     },
     "word-wrap": {
-      "version": "1.2.3",
-      "resolved": "https://registry.npmjs.org/word-wrap/-/word-wrap-1.2.3.tgz",
-      "integrity": "sha512-Hz/mrNwitNRh/HUAtM/VT/5VH+ygD6DV7mYKZAtHOrbs8U7lvPS6xf7EJKMF0uW1KJCl0H701g3ZGus+muE5vQ==",
+      "version": "1.2.4",
+      "resolved": "https://registry.npmjs.org/word-wrap/-/word-wrap-1.2.4.tgz",
+      "integrity": "sha512-2V81OA4ugVo5pRo46hAoD2ivUJx8jXmWXfUkY4KFNw0hEptvN0QfH3K4nHiwzGeKl5rFKedV48QVoqYavy4YpA==",
       "dev": true
     },
     "wordwrapjs": {
diff --git a/src/duration.ts b/src/duration.ts
index 5dc7a3c..a0529e3 100644
--- a/src/duration.ts
+++ b/src/duration.ts
@@ -151,33 +151,45 @@ export function roundToSingleUnit(duration: Duration, {relativeTo = Date.now()}:
   if (!days && hours >= 21) days += Math.round(hours / 24)
   if (days || weeks || months || years) hours = 0
 
+  // Resolve calendar dates
   const currentYear = relativeTo.getFullYear()
   let currentMonth = relativeTo.getMonth()
   const currentDate = relativeTo.getDate()
-  if (days >= 27 || (years + months && days)) {
-    relativeTo.setDate(currentDate + days * sign)
-    months += Math.abs(
-      relativeTo.getFullYear() >= currentYear
-        ? relativeTo.getMonth() - currentMonth
-        : relativeTo.getMonth() - currentMonth - 12,
-    )
-    if (months) {
-      days = 0
+  if (days >= 27 || years + months + days) {
+    const newDate = new Date(relativeTo)
+    newDate.setFullYear(currentYear + years * sign)
+    newDate.setMonth(currentMonth + months * sign)
+    newDate.setDate(currentDate + days * sign)
+    const yearDiff = newDate.getFullYear() - relativeTo.getFullYear()
+    const monthDiff = newDate.getMonth() - relativeTo.getMonth()
+    const daysDiff = Math.abs(Math.round((Number(newDate) - Number(relativeTo)) / 86400000))
+    const monthsDiff = Math.abs(yearDiff * 12 + monthDiff)
+    if (daysDiff < 27) {
+      if (days >= 6) {
+        weeks += Math.round(days / 7)
+        days = 0
+      } else {
+        days = daysDiff
+      }
+      months = years = 0
+    } else if (monthsDiff < 11) {
+      months = monthsDiff
+      years = 0
+    } else {
+      months = 0
+      years = yearDiff * sign
     }
+    if (months || years) days = 0
     currentMonth = relativeTo.getMonth()
   }
-
-  if (days >= 6) weeks += Math.round(days / 7)
-  if (weeks || months || years) days = 0
+  if (years) months = 0
 
   if (weeks >= 4) months += Math.round(weeks / 4)
   if (months || years) weeks = 0
-
-  if (months >= 11 || (years && months)) {
-    relativeTo.setMonth(relativeTo.getMonth() + months * sign)
-    years += Math.abs(currentYear - relativeTo.getFullYear())
+  if (days && weeks && !months && !years) {
+    weeks += Math.round(days / 7)
+    days = 0
   }
-  if (years) months = 0
 
   return new Duration(
     years * sign,
diff --git a/test/duration.ts b/test/duration.ts
index ef96d97..d90c490 100644
--- a/test/duration.ts
+++ b/test/duration.ts
@@ -293,6 +293,7 @@ suite('duration', function () {
       ['P9M20DT25H', 'P10M', {relativeTo: new Date('2023-01-12T00:00:00Z')}],
       ['P11M', 'P1Y', {relativeTo: new Date('2022-11-01T00:00:00Z')}],
       ['-P11M', '-P1Y', {relativeTo: new Date('2022-11-01T00:00:00Z')}],
+      ['-P11M15D', '-P1Y', {relativeTo: new Date('2024-01-06T00:00:00')}],
       ['P1Y4D', 'P1Y', {relativeTo: new Date('2022-11-01T00:00:00Z')}],
       ['P1Y5M13D', 'P1Y', {relativeTo: new Date('2023-01-01T00:00:00Z')}],
       ['P1Y5M15D', 'P1Y', {relativeTo: new Date('2023-01-01T00:00:00Z')}],
@@ -308,7 +309,12 @@ suite('duration', function () {
           relativeTo: new Date('2022-01-01T00:00:00Z'),
         },
       ],
-      ['-P27D', '-P1M', {relativeTo: new Date('2023-02-28T00:00:00Z')}],
+      ['-P27D', '-P27D', {relativeTo: new Date('2023-02-28T00:00:00Z')}],
+      ['-P27D', '-P1M', {relativeTo: new Date('2023-02-27T00:00:00Z')}],
+      ['P1Y2M1D', 'P2Y', {relativeTo: new Date('2022-12-31T12:00:00.000Z')}],
+      ['-P1Y8D', '-P1Y', {relativeTo: new Date('2024-01-11T12:00:00.000Z')}],
+      ['-P1Y7DT19H43M19S', '-P1Y', {relativeTo: new Date('2024-01-11T12:00:00.000Z')}],
+      ['-P1Y11D', '-P2Y', {relativeTo: new Date('2024-01-11T12:00:00.000Z')}],
     ])
     for (const [input, expected, opts] of roundTests) {
       test(`roundToSingleUnit(${input}) === ${expected}`, () => {
diff --git a/test/relative-time.js b/test/relative-time.js
index 1f20571..c49d731 100644
--- a/test/relative-time.js
+++ b/test/relative-time.js
@@ -482,7 +482,7 @@ suite('relative-time', function () {
       time.setAttribute('datetime', datetime)
       time.setAttribute('format', 'micro')
       await Promise.resolve()
-      assert.equal(time.shadowRoot.textContent, '10y')
+      assert.equal(time.shadowRoot.textContent, '11y')
     })
 
     test('micro formats future times', async () => {
@@ -2416,14 +2416,14 @@ suite('relative-time', function () {
         datetime: '2024-03-01T12:00:00.000Z',
         tense: 'future',
         format: 'auto',
-        expected: 'in 3 years',
+        expected: 'in 2 years',
       },
       {
         reference: '2022-12-31T12:00:00.000Z',
         datetime: '2024-03-01T12:00:00.000Z',
         tense: 'future',
         format: 'micro',
-        expected: '3y',
+        expected: '2y',
       },
       {
         reference: '2021-04-24T12:00:00.000Z',
@@ -2432,6 +2432,13 @@ suite('relative-time', function () {
         format: 'micro',
         expected: '2y',
       },
+      {
+        reference: '2024-01-04T12:00:00.000Z',
+        datetime: '2020-02-16T16:16:41.000Z',
+        tense: 'past',
+        format: 'auto',
+        expected: '4 years ago',
+      },
     ])
 
     for (const {