diff --git a/src/utils.ts b/src/utils.ts
index 3089faf..87b6fcb 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -30,6 +30,8 @@ export const sanitizeLocales = (...locales: any[]): string[] | [] => {
     let current = `${locale}`.toLowerCase();
     try {
       [current] = Intl.Collator.supportedLocalesOf(locale);
+
+      if (!current) throw new Error(`[i18n]: '${locale}' is non-standard.`);
     } catch (error) {
       console.warn(`[i18n]: Non-standard locale provided: '${locale}'. Check your 'translations' and 'loaders' in i18n config...`);
     }
diff --git a/tests/data/index.ts b/tests/data/index.ts
index d628b92..5652765 100644
--- a/tests/data/index.ts
+++ b/tests/data/index.ts
@@ -26,8 +26,8 @@ export const CONFIG: Config.T = {
     },
     {
       key: 'common',
-      locale: 'cs',
-      loader: async () => (import('../data/translations/cs/common.json')),
+      locale: 'zh-Hans',
+      loader: async () => (import('../data/translations/zh-Hans/common.json')),
     },
   ],
 };
\ No newline at end of file
diff --git a/tests/data/translations/index.ts b/tests/data/translations/index.ts
index 1684b65..b812014 100644
--- a/tests/data/translations/index.ts
+++ b/tests/data/translations/index.ts
@@ -3,7 +3,8 @@ import type { Translations } from '../../../src/types';
 
 import * as common from './en/common.json';
 import * as route from './en/route.json';
-import * as common_cs from './cs/common.json';
+import * as common_ku from './ku/common.json';
+import * as common_zhHans from './zh-Hans/common.json';
 
 export default ({
   en: toDotNotation({
@@ -11,7 +12,10 @@ export default ({
     route1: route,
     route2: route,
   }),
-  cs: toDotNotation({
-    common: common_cs,
+  'zh-Hans': toDotNotation({
+    common: common_zhHans,
+  }),
+  ku: toDotNotation({
+    common: common_ku,
   }),
 }) as Translations.T;
\ No newline at end of file
diff --git a/tests/data/translations/cs/common.json b/tests/data/translations/ku/common.json
similarity index 100%
rename from tests/data/translations/cs/common.json
rename to tests/data/translations/ku/common.json
diff --git a/tests/data/translations/zh-Hans/common.json b/tests/data/translations/zh-Hans/common.json
new file mode 100644
index 0000000..3cf6df0
--- /dev/null
+++ b/tests/data/translations/zh-Hans/common.json
@@ -0,0 +1,9 @@
+{
+  "no_placeholder": "NO_PLACEHOLDER",
+  "placeholder": "VALUES: {{value}}, {{value;}}, {{ value }}, {{ value; }}",
+  "modifier_test": "VALUES: {{value; option1:VALUE1; option2:VALUE2; default:DEFAULT VALUE;}}, {{ value ; option1 : VALUE1 ; option2 : VALUE2 ; default : DEFAULT VALUE ;}}",
+  "custom_modifier": "{{date:date;}}",
+  "modifier_number": "{{value:number;}}",
+  "modifier_date": "{{value:date;}}",
+  "modifier_ago": "{{value:ago;}}"
+}
\ No newline at end of file
diff --git a/tests/specs/index.spec.ts b/tests/specs/index.spec.ts
index ae42b9f..1bc4ea0 100644
--- a/tests/specs/index.spec.ts
+++ b/tests/specs/index.spec.ts
@@ -117,6 +117,31 @@ describe('i18n instance', () => {
     const $locale = locale.get();
     expect($locale).toBe(initLocale.toLocaleLowerCase());
   });
+  it('`locale` can be non-standard', async () => {
+    const nonStandardLocale = 'ku';
+    const { loading, locale, locales, setRoute, initialized, translations } = new i18n({ loaders: [{ key: 'common', locale: `${nonStandardLocale}`.toUpperCase(), loader: () => import(`../data/translations/${nonStandardLocale}/common.json`) }], parser });
+    await setRoute('');
+    locale.set(nonStandardLocale);
+
+    const $loading = loading.get();
+    expect($loading).toBe(true);
+
+    await loading.toPromise();
+
+    const $initialized = get(initialized);
+    expect($initialized).toBe(true);
+
+    const $locale = locale.get();
+    expect($locale).toBe(nonStandardLocale);
+
+    const $locales = locales.get();
+    expect($locales).toContainEqual(nonStandardLocale);
+
+    const $translations = translations.get();
+    expect($translations[nonStandardLocale]).toEqual(
+      expect.objectContaining(filterTranslationKeys(TRANSLATIONS[nonStandardLocale], ['common'])),
+    );
+  });
   it('`getTranslationProps` method works', async () => {
     const { initialized, getTranslationProps } = new i18n({ loaders, parser });