diff --git a/src/modules/chat/hooks/useChat.js b/src/modules/chat/hooks/useChat.js
index 9201cba..547390e 100644
--- a/src/modules/chat/hooks/useChat.js
+++ b/src/modules/chat/hooks/useChat.js
@@ -636,7 +636,7 @@ export function useChat() {
       const assignment = await assignWhatsappChat({
         chatId: contactId,
         userId: String(currentUserId),
-        areaId,
+        areaId: areaId != null ? String(areaId) : undefined,
       });
       updateContact(contactId, (contact) => ({
         ...contact,