diff --git a/src/hooks/useDatePicker.spec.tsx b/src/hooks/useDatePicker.spec.tsx
index 8decdfc..cc853c3 100644
--- a/src/hooks/useDatePicker.spec.tsx
+++ b/src/hooks/useDatePicker.spec.tsx
@@ -3,7 +3,7 @@ import { render } from '@testing-library/react'
 import { renderHook } from '@testing-library/react-hooks'
 import React from 'react'
 import { SupportedCalendar } from '../types'
-import { formatDate } from '../utils'
+import { convertToIso8601, formatDate } from '../utils'
 import localisationHelpers from '../utils/localisationHelpers'
 import { useDatePicker, UseDatePickerReturn } from './useDatePicker'
 
@@ -510,34 +510,21 @@ describe('clicking a day', () => {
     }
     it('should call the callback with correct info for Gregorian calendar', () => {
         const date = '2018-01-22'
-        const { calendarDate, calendarDateString } = renderForClick({
+        const { calendarDateString } = renderForClick({
             calendar: 'gregory',
             date,
         })
-        expect(calendarDate.toString()).toEqual(
-            '2018-01-22T00:00:00+02:00[Africa/Khartoum][u-ca=gregory]'
-        )
         expect(calendarDateString).toEqual('2018-01-22')
     })
     it('should call the callback with correct info for Ethiopic calendar', () => {
         const date = '2015-13-02'
-        const { calendarDate, calendarDateString } = renderForClick({
+        const { calendarDateString } = renderForClick({
             calendar: 'ethiopic',
             date,
         })
         expect(calendarDateString).toEqual('2015-13-02')
-        expect(
-            calendarDate.withCalendar('iso8601').toLocaleString('en-GB')
-        ).toMatch('07/09/2023')
-
-        expect(
-            calendarDate.toLocaleString('en-GB', {
-                month: 'long',
-                year: 'numeric',
-                day: 'numeric',
-                calendar: 'ethiopic',
-            })
-        ).toEqual('2 Pagumen 2015 ERA1')
+        const calendarDate = convertToIso8601(calendarDateString, 'ethiopic')
+        expect(calendarDate).toEqual({ day: 7, month: 9, year: 2023 })
     })
     it('should call the callback with correct info for a custom (Nepali) calendar', () => {
         const date = '2077-12-30'
@@ -548,7 +535,11 @@ describe('clicking a day', () => {
         expect(calendarDateString).toEqual('2077-12-30')
         expect(
             localisationHelpers.localiseMonth(
-                calendarDate,
+                {
+                    year: 20777,
+                    month: 12,
+                    day: 30,
+                },
                 {
                     locale: 'en-NP',
                     calendar: 'nepali',
diff --git a/src/hooks/useDatePicker.ts b/src/hooks/useDatePicker.ts
index d3b2284..5288854 100644
--- a/src/hooks/useDatePicker.ts
+++ b/src/hooks/useDatePicker.ts
@@ -21,10 +21,8 @@ type DatePickerOptions = {
     date: string
     options: PickerOptions
     onDateSelect: ({
-        calendarDate,
         calendarDateString,
     }: {
-        calendarDate: Temporal.ZonedDateTime
         calendarDateString: string
     }) => void
     minDate?: string
@@ -150,7 +148,6 @@ export const useDatePicker: UseDatePickerHookType = ({
     const selectDate = useCallback(
         (zdt: Temporal.ZonedDateTime) => {
             onDateSelect({
-                calendarDate: zdt,
                 calendarDateString: formatDate(zdt, undefined, date.format),
             })
         },
diff --git a/src/utils/localisationHelpers.ts b/src/utils/localisationHelpers.ts
index da44e16..01258d0 100644
--- a/src/utils/localisationHelpers.ts
+++ b/src/utils/localisationHelpers.ts
@@ -113,7 +113,11 @@ const localiseWeekLabel = (
 }
 
 const localiseMonth = (
-    zdt: Temporal.ZonedDateTime | Temporal.PlainYearMonth | Temporal.PlainDate,
+    zdt:
+        | Temporal.ZonedDateTime
+        | Temporal.PlainYearMonth
+        | Temporal.PlainDate
+        | Temporal.PlainDateLike,
     localeOptions: PickerOptions,
     format: Intl.DateTimeFormatOptions
 ) => {