diff --git a/src/format/formatters/index.ts b/src/format/formatters/index.ts
index e022a83..f0cae45 100644
--- a/src/format/formatters/index.ts
+++ b/src/format/formatters/index.ts
@@ -97,10 +97,10 @@ export const formatters: Record<
   },
 }
 
-function getTimeZoneOffset(timeZone: string | undefined, originalDate: Date|undefined = undefined) {
+function getTimeZoneOffset(timeZone: string | undefined, originalDate?: Date) {
   const timeZoneOffset = timeZone
     ? tzParseTimezone(timeZone, originalDate, true) / MILLISECONDS_IN_MINUTE
-    : (originalDate?.getTimezoneOffset() ?? 0)
+    : originalDate?.getTimezoneOffset() ?? 0
   if (Number.isNaN(timeZoneOffset)) {
     throw new RangeError('Invalid time zone specified: ' + timeZone)
   }
diff --git a/src/getTimezoneOffset/index.ts b/src/getTimezoneOffset/index.ts
index 9e4a8b1..90f1469 100644
--- a/src/getTimezoneOffset/index.ts
+++ b/src/getTimezoneOffset/index.ts
@@ -26,6 +26,6 @@ import { tzParseTimezone } from '../_lib/tzParseTimezone/index.js'
  * const result = getTimezoneOffset('America/New_York', new Date(2016, 6, 1))
  *   //=> -14400000 (-4 * 60 * 60 * 1000)
  */
-export function getTimezoneOffset(timeZone: string, date: Date | number): number {
+export function getTimezoneOffset(timeZone: string, date?: Date | number): number {
   return -tzParseTimezone(timeZone, date)
 }