diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index fb24ce1..8406a63 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -9,4 +9,3 @@ updates:
       # update-package-lock workflow already handles minor/patch updates
       - dependency-name: "*"
         update-types: ["version-update:semver-minor", "version-update:semver-patch"]
-      - dependency-name: "@formatjs/intl-pluralrules"
diff --git a/lib/PluralRules.js b/lib/PluralRules.js
new file mode 100644
index 0000000..b2bba60
--- /dev/null
+++ b/lib/PluralRules.js
@@ -0,0 +1,78 @@
+const localeData = {
+	mi: {
+		aliases: ['mri', 'mao'],
+		options: {
+			cardinal: {
+				locale: 'mi',
+				pluralCategories : [ 'one', 'other' ],
+				shim: true
+			},
+			ordinal: {
+				locale: 'mi',
+				pluralCategories : [ 'other' ],
+				shim: true
+			},
+		},
+		select(n, ord) {
+			return !ord && n === 1 ? 'one' : 'other';
+		}
+	}
+};
+
+function getCanonicalLocales(locales) {
+	const mappedLocales = [locales].flat().map(locale => {
+		for (const canonicalLocale in localeData) {
+			if (localeData[canonicalLocale].aliases.includes(locale)) {
+				return canonicalLocale;
+			}
+		}
+		return locale;
+	});
+	return Intl.getCanonicalLocales(mappedLocales);
+}
+
+class PluralRules extends Intl.PluralRules {
+
+	static shim = true;
+	static supportedLocalesOf(locales) {
+		return [locales].flat().map(l => {
+			const canonicalLocale = getCanonicalLocales(l)[0];
+			if (localeData[canonicalLocale]) {
+				return canonicalLocale;
+			}
+			return super.supportedLocalesOf(l);
+		}).flat();
+	}
+	#localeData;
+	#locale;
+	#type;
+
+	constructor(locales, options = {}) {
+		super(locales, options);
+		this.#locale = PluralRules.supportedLocalesOf(locales)[0];
+		this.#type = options.type ?? 'cardinal';
+		if (localeData[this.#locale]) {
+			this.#localeData = localeData[this.#locale];
+		}
+	}
+
+	resolvedOptions() {
+		return { ...super.resolvedOptions(), ...this.#localeData?.options[this.#type] };
+	}
+
+	select(n) {
+		if (this.#localeData) {
+			return this.#localeData.select(n, this.#type === 'ordinal');
+		} else {
+			return super.select(n);
+		}
+	}
+
+}
+
+Object.defineProperty(Intl, 'PluralRules', {
+	value: PluralRules,
+	writable: true,
+	enumerable: false,
+	configurable: true,
+});
diff --git a/lib/localize.js b/lib/localize.js
index 66259f0..2b42e48 100644
--- a/lib/localize.js
+++ b/lib/localize.js
@@ -1,5 +1,5 @@
-import '@formatjs/intl-pluralrules/dist-es6/polyfill-locales.js';
-import { defaultLocale as fallbackLang, getDocumentLocaleSettings, supportedLangpacks } from '../lib/common.js';
+import './PluralRules.js';
+import { defaultLocale as fallbackLang, getDocumentLocaleSettings, supportedLangpacks } from './common.js';
 import { getLocalizeOverrideResources } from '../helpers/getLocalizeResources.js';
 import IntlMessageFormat from 'intl-messageformat';
 
diff --git a/package-lock.json b/package-lock.json
index b7604bb..a8b0fc9 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,7 +9,6 @@
       "version": "3.18.0",
       "license": "Apache-2.0",
       "dependencies": {
-        "@formatjs/intl-pluralrules": "^1",
         "intl-messageformat": "^10"
       },
       "devDependencies": {
@@ -583,6 +582,7 @@
       "version": "1.5.9",
       "resolved": "https://registry.npmjs.org/@formatjs/intl-pluralrules/-/intl-pluralrules-1.5.9.tgz",
       "integrity": "sha512-37E1ZG+Oqo3qrpUfumzNcFTV+V+NCExmTkkQ9Zw4FSlvJ4WhbbeYdieVapUVz9M0cLy8XrhCkfuM/Kn03iKReg==",
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "@formatjs/intl-utils": "^2.3.0"
@@ -593,6 +593,7 @@
       "resolved": "https://registry.npmjs.org/@formatjs/intl-utils/-/intl-utils-2.3.0.tgz",
       "integrity": "sha512-KWk80UPIzPmUg+P0rKh6TqspRw0G6eux1PuJr+zz47ftMaZ9QDwbGzHZbtzWkl5hgayM/qrKRutllRC7D/vVXQ==",
       "deprecated": "the package is rather renamed to @formatjs/ecma-abstract with some changes in functionality (primarily selectUnit is removed and we don't plan to make any further changes to this package",
+      "dev": true,
       "license": "MIT"
     },
     "node_modules/@hapi/bourne": {
diff --git a/package.json b/package.json
index e4aa8b6..d62471e 100644
--- a/package.json
+++ b/package.json
@@ -44,7 +44,6 @@
     "sinon": "^19.0.2"
   },
   "dependencies": {
-    "@formatjs/intl-pluralrules": "^1",
     "intl-messageformat": "^10"
   }
 }
diff --git a/test/PluralRules.test.js b/test/PluralRules.test.js
new file mode 100644
index 0000000..ec95ad4
--- /dev/null
+++ b/test/PluralRules.test.js
@@ -0,0 +1,79 @@
+import '../lib/PluralRules.js';
+import { expect } from '@brightspace-ui/testing';
+import { getDocumentLocaleSettings } from '../lib/common.js';
+
+describe('PluralRules', () => {
+
+	const documentLocaleSettings = getDocumentLocaleSettings();
+
+	afterEach(() => documentLocaleSettings.reset());
+
+	it('extends native Intl.PluralRules', () => {
+		const native = Object.getPrototypeOf(Intl.PluralRules);
+		expect(Intl.PluralRules.shim).to.be.true;
+		expect(native).to.have.property('name', 'PluralRules');
+		expect(native).to.not.have.property('shim');
+	});
+
+	it('uses native data by default', () => {
+		const shim = new Intl.PluralRules('cy');
+		const native = new (Object.getPrototypeOf(Intl.PluralRules))('cy');
+		expect(shim.resolvedOptions()).to.deep.equal(native.resolvedOptions());
+		expect(shim.select(2)).to.equal('two');
+	});
+
+	it('resolves to canonical locales', () => {
+		expect(new Intl.PluralRules('mao').resolvedOptions().locale).to.equal('mi');
+		expect(new Intl.PluralRules('mri').resolvedOptions().locale).to.equal('mi');
+		expect(new Intl.PluralRules(['abcdefg', 'mri']).resolvedOptions().locale).to.equal('mi');
+	});
+
+	it('includes custom locales as supported', () => {
+		expect(Intl.PluralRules.supportedLocalesOf(['abc', 'mao', 'en'])).to.deep.equal(['mi', 'en']);
+	});
+
+	[
+		{
+			locale: 'mi',
+			type: 'cardinal',
+			options: {
+				locale: 'mi',
+				shim: true,
+				pluralCategories: [ 'one', 'other' ]
+			},
+			select: {
+				one: [1],
+				other: [0, 2, 3, 11]
+			}
+		},
+		{
+			locale: 'mi',
+			type: 'ordinal',
+			options: {
+				locale: 'mi',
+				shim: true,
+				pluralCategories: [ 'other' ]
+			},
+			select: {
+				other: [0, 1, 2, 3, 11]
+			}
+		}
+	].forEach(({ locale, type, options, select }) => {
+
+		documentLocaleSettings.language = locale;
+		const pluralRules = new Intl.PluralRules(locale, { type });
+
+		it(`should use custom ${type} data for "${locale}"`, () => {
+			expect(pluralRules.resolvedOptions()).to.deep.include(options);
+		});
+
+		it(`should select the correct ${type} number categories for "${locale}"`, () => {
+			options.pluralCategories.forEach(cat => {
+				select[cat].forEach(num => {
+					expect(pluralRules.select(num)).to.equal(cat);
+				});
+			});
+		});
+	});
+
+});
diff --git a/test/localize.test.js b/test/localize.test.js
index e9ba0a2..a45d0be 100644
--- a/test/localize.test.js
+++ b/test/localize.test.js
@@ -9,6 +9,10 @@ const resources = {
 	},
 	'en-gb': {
 		basic: '{employerName} is my employer, but British!'
+	},
+	mi: {
+		plural: '{a, plural, one {one} other {other}}',
+		ordinal: '{a, selectordinal, one {one} other {other}}'
 	}
 };
 
@@ -79,6 +83,24 @@ describe('Localize', () => {
 			expect(localized).to.equal('This message has 2 arguments');
 		});
 
+		it('should select the correct category for shimmed locales', async() => {
+			await localizer.ready;
+			document.documentElement.lang = 'mi';
+			await updatePromise;
+
+			const pluralOne = localizer.localize('plural', { a: 1 });
+			expect(pluralOne).to.equal('one');
+
+			const pluralTwo = localizer.localize('plural', { a: 2 });
+			expect(pluralTwo).to.equal('other');
+
+			const ordinalOne = localizer.localize('ordinal', { a: 1 });
+			expect(ordinalOne).to.equal('other');
+
+			const ordinalTwo = localizer.localize('ordinal', { a: 2 });
+			expect(ordinalTwo).to.equal('other');
+		});
+
 	});
 
 	describe('localizeHTML()', () => {