diff --git a/src/hooks/useDatePicker.spec.tsx b/src/hooks/useDatePicker.spec.tsx
index cc853c3..ba97c14 100644
--- a/src/hooks/useDatePicker.spec.tsx
+++ b/src/hooks/useDatePicker.spec.tsx
@@ -271,24 +271,16 @@ describe('useDatePicker hook', () => {
         })
     })
     describe('highlighting today', () => {
-        const getDayByDate: (
+        const getDayByDate = (
             calendarWeekDays: {
                 isToday: boolean
-                zdt: Temporal.ZonedDateTime
+                dateValue: string
             }[][],
             dayToFind: string
-        ) => { calendarDate: string; isToday: boolean }[] = (
-            calendarWeekDays,
-            dayToFind
         ) => {
-            const days = calendarWeekDays
-                .flatMap((week) => week)
-                .map((day) => ({
-                    ...day,
-                    calendarDate: formatDate(day.zdt, undefined, 'YYYY-MM-DD'),
-                }))
-
-            return days.filter((day) => day.calendarDate === dayToFind)
+            const days = calendarWeekDays.flatMap((week) => week)
+
+            return days.filter((day) => day.dateValue === dayToFind)
         }
 
         it('should highlight today date in a an ethiopic calendar', () => {
@@ -494,11 +486,7 @@ describe('clicking a day', () => {
 
         // find and click the day passed to the calendar
         for (let i = 0; i < days.length; i++) {
-            const formattedDate = formatDate(
-                days[i].zdt,
-                undefined,
-                'YYYY-MM-DD'
-            )
+            const formattedDate = days[i].dateValue
             if (formattedDate === date) {
                 days[i].onClick()
                 break
@@ -528,7 +516,7 @@ describe('clicking a day', () => {
     })
     it('should call the callback with correct info for a custom (Nepali) calendar', () => {
         const date = '2077-12-30'
-        const { calendarDate, calendarDateString } = renderForClick({
+        const { calendarDateString } = renderForClick({
             calendar: 'nepali',
             date,
         })
diff --git a/src/hooks/useDatePicker.ts b/src/hooks/useDatePicker.ts
index 5288854..8174bed 100644
--- a/src/hooks/useDatePicker.ts
+++ b/src/hooks/useDatePicker.ts
@@ -34,7 +34,7 @@ type DatePickerOptions = {
 export type UseDatePickerReturn = UseNavigationReturnType & {
     weekDayLabels: string[]
     calendarWeekDays: {
-        zdt: Temporal.ZonedDateTime
+        dateValue: string
         label: string | number
         onClick: () => void
         isSelected: boolean | undefined
@@ -185,10 +185,10 @@ export const useDatePicker: UseDatePickerHookType = ({
         temporalCalendar,
         temporalTimeZone,
     ])
-    return {
+    const result: UseDatePickerReturn = {
         calendarWeekDays: calendarWeekDaysZdts.map((week) =>
             week.map((weekDayZdt) => ({
-                zdt: weekDayZdt,
+                dateValue: formatDate(weekDayZdt, undefined, format),
                 label: localisationHelpers.localiseWeekLabel(
                     weekDayZdt.withCalendar(localeOptions.calendar),
                     localeOptions
@@ -208,4 +208,6 @@ export const useDatePicker: UseDatePickerHookType = ({
         ...navigation,
         weekDayLabels,
     }
+
+    return result
 }
diff --git a/src/utils/localisationHelpers.ts b/src/utils/localisationHelpers.ts
index 01258d0..1157dc2 100644
--- a/src/utils/localisationHelpers.ts
+++ b/src/utils/localisationHelpers.ts
@@ -131,7 +131,7 @@ const localiseMonth = (
     )
 
     return isCustom
-        ? customLocale?.monthNames[zdt.month - 1]
+        ? customLocale?.monthNames[zdt.month! - 1]
         : zdt.toLocaleString(localeOptions.locale, format)
 }