diff --git a/app/api/chat/route.ts b/app/api/chat/route.ts
index beec80f..36087fd 100644
--- a/app/api/chat/route.ts
+++ b/app/api/chat/route.ts
@@ -40,7 +40,7 @@ export async function POST(req: Request) {
   const stream = OpenAIStream(res, {
     async onCompletion(completion) {
       const title = json.messages[0].content.substring(0, 100)
-      const userId = session.user.id
+      const userId = session.user?.id
       const id = json.id ?? nanoid()
       const createdAt = Date.now()
       const path = `/chat/${id}`
diff --git a/index.d.ts b/next-auth.d.ts
similarity index 93%
rename from index.d.ts
rename to next-auth.d.ts
index 5b3f52b..918e14d 100644
--- a/index.d.ts
+++ b/next-auth.d.ts
@@ -7,7 +7,7 @@ declare module 'next-auth' {
   interface Session {
     user: {
       /** The user's postal address. */
-      address: string
+      id: string
     } & DefaultSession['user']
   }
 }