diff --git a/packages/use-i18n/src/__tests__/usei18n.tsx b/packages/use-i18n/src/__tests__/usei18n.tsx
index ebe52f686..112792b5a 100644
--- a/packages/use-i18n/src/__tests__/usei18n.tsx
+++ b/packages/use-i18n/src/__tests__/usei18n.tsx
@@ -314,10 +314,6 @@ describe('i18n hook', () => {
       }),
     ).toEqual('$2.00')
 
-    expect(
-      result.current.formatNumber(1.234, { style: 'unit', unit: 'kilobyte' }),
-    ).toEqual('1.234 kB')
-
     act(() => {
       result.current.switchLocale('fr')
     })
@@ -552,6 +548,6 @@ describe('i18n hook', () => {
     expect(result.current.dateFnsLocale).toBe(undefined)
     await waitForNextUpdate()
 
-    expect(result.current.dateFnsLocale.code).toEqual('en-GB')
+    expect(result.current.dateFnsLocale?.code).toEqual('en-GB')
   })
 })
diff --git a/packages/use-i18n/src/usei18n.tsx b/packages/use-i18n/src/usei18n.tsx
index a6fb76333..cbc2a6a6f 100644
--- a/packages/use-i18n/src/usei18n.tsx
+++ b/packages/use-i18n/src/usei18n.tsx
@@ -57,32 +57,31 @@ const getCurrentLocale = ({
 interface Context {
   currentLocale: string
   dateFnsLocale?: Locale,
-  datetime?: (date: Date | number, options?: Intl.DateTimeFormatOptions) => string,
-  formatDate?: (value: Date | number | string, options: FormatDateOptions) => string,
-  formatList?: (listFormat: [string | undefined], options?: Intl.ListFormatOptions) => string,
-  formatNumber?: (numb: number, options?: Intl.NumberFormatOptions) => string,
-  formatUnit?: (value: number, options: FormatUnitOptions) => string,
-  loadTranslations?: (namespace: string, load?: LoadTranslationsFn) => Promise<string>,
-  locales?: string[],
-  namespaces?: string[],
-  namespaceTranslation?: (namespace: string, t?: TranslateFn) => TranslateFn
-  relativeTime?: (date: Date | number, options?: {
+  datetime: (date: Date | number, options?: Intl.DateTimeFormatOptions) => string,
+  formatDate: (value: Date | number | string, options: FormatDateOptions) => string,
+  formatList: (listFormat: string[], options?: Intl.ListFormatOptions) => string,
+  formatNumber: (numb: number, options?: Intl.NumberFormatOptions) => string,
+  formatUnit: (value: number, options: FormatUnitOptions) => string,
+  loadTranslations: (namespace: string, load?: LoadTranslationsFn) => Promise<string>,
+  locales: string[],
+  namespaces: string[],
+  namespaceTranslation: (namespace: string, t?: TranslateFn) => TranslateFn
+  relativeTime: (date: Date | number, options?: {
     includeSeconds?: boolean;
     addSuffix?: boolean;
   }) => string,
-  relativeTimeStrict?: (date: Date | number, options?: {
+  relativeTimeStrict: (date: Date | number, options?: {
     addSuffix?: boolean;
     unit?: 'second' | 'minute' | 'hour' | 'day' | 'month' | 'year';
     roundingMethod?: 'floor' | 'ceil' | 'round';
   }) => string,
-  setTranslations?: React.Dispatch<React.SetStateAction<TranslationsByLocales>>,
-  switchLocale?: (locale: string) => void,
-  t?: TranslateFn,
-  translations?: TranslationsByLocales,
+  setTranslations: React.Dispatch<React.SetStateAction<TranslationsByLocales>>,
+  switchLocale: (locale: string) => void,
+  t: TranslateFn,
+  translations: TranslationsByLocales,
 }
 
-// @ts-expect-error we force the context to undefined, should be corrected with default values
-const I18nContext = createContext<Context>(undefined)
+const I18nContext = createContext<Context | undefined>(undefined)
 
 export const useI18n = (): Context => {
   const context = useContext(I18nContext)
@@ -214,7 +213,7 @@ const I18nContextProvider = ({
   )
 
   const formatList = useCallback(
-    (listFormat: [string | undefined], options?: Intl.ListFormatOptions) =>
+    (listFormat: string[], options?: Intl.ListFormatOptions) =>
     formatters.getListFormat(currentLocale, options).format(listFormat),
     [currentLocale],
   )
diff --git a/types/intl.d.ts b/types/intl.d.ts
index 5bb566bd4..5ec2230e9 100644
--- a/types/intl.d.ts
+++ b/types/intl.d.ts
@@ -1,12 +1,12 @@
 declare namespace Intl {
   interface ListFormatOptions {
-    localeMatcher: 'best fit' | 'lookup'
-    type: 'conjunction' | 'disjunction' | 'unit'
-    style: 'long' | 'short' | 'narrow'
+    localeMatcher?: 'best fit' | 'lookup'
+    type?: 'conjunction' | 'disjunction' | 'unit'
+    style?: 'long' | 'short' | 'narrow'
   }
 
   interface ListFormat {
-    format: (items: [string?]) => string;
+    format: (items: string[]) => string;
   }
 
   const ListFormat: {