diff --git a/apps/blogai/app/[locale]/auth/sign-up/mix-signup.tsx b/apps/blogai/app/[locale]/auth/sign-up/mix-signup.tsx
index 91fab73..2578f4b 100644
--- a/apps/blogai/app/[locale]/auth/sign-up/mix-signup.tsx
+++ b/apps/blogai/app/[locale]/auth/sign-up/mix-signup.tsx
@@ -140,7 +140,7 @@ export function MixSignUp(props: {
         <form className="grid gap-2" onSubmit={(e) => {
           e.preventDefault();
           const regname = new FormData(e.currentTarget).get("regname");
-          const refer = new FormData(e.currentTarget).get("referreredit")
+          const refer = new FormData(e.currentTarget).get("referreredit") || "";
 
           if (
             typeof regname !== "string"