diff --git a/web/src/lib/modals/PersonEditBirthDateModal.svelte b/web/src/lib/modals/PersonEditBirthDateModal.svelte
index 4d6fa47ff..6199c7b48 100644
--- a/web/src/lib/modals/PersonEditBirthDateModal.svelte
+++ b/web/src/lib/modals/PersonEditBirthDateModal.svelte
@@ -15,7 +15,7 @@
   let birthDate = $derived(person.birthDate ? DateTime.fromISO(person.birthDate) : undefined);
 
   const onSubmit = async () => {
-    const success = await handleUpdatePersonBirthDate(person, birthDate?.toISODate() ?? '');
+    const success = await handleUpdatePersonBirthDate(person, birthDate?.toISODate() ?? null);
     if (success) {
       onClose();
     }
diff --git a/web/src/lib/services/person.service.ts b/web/src/lib/services/person.service.ts
index 7cdc4af54..c51a7d42b 100644
--- a/web/src/lib/services/person.service.ts
+++ b/web/src/lib/services/person.service.ts
@@ -99,7 +99,7 @@ const handleShowPerson = async (person: { id: string }) => {
   }
 };
 
-export const handleUpdatePersonBirthDate = async (person: PersonResponseDto, birthDate: string) => {
+export const handleUpdatePersonBirthDate = async (person: PersonResponseDto, birthDate: string | null) => {
   const $t = await getFormatter();
 
   try {