diff --git a/src/auth/auth.service.ts b/src/auth/auth.service.ts
index 1429e39..73d456d 100644
--- a/src/auth/auth.service.ts
+++ b/src/auth/auth.service.ts
@@ -129,7 +129,7 @@ export class AuthService {
       secure: isProduction || cookieSecure,
       sameSite: "none" as const,
       path: isRefreshToken ? "/auth/refresh" : "/",
-      domain: domain,
+      domain: domain?.startsWith(".") ? domain : `.${domain}`,
       maxAge: isRefreshToken ? 7 * 24 * 60 * 60 * 1000 : 15 * 60 * 1000,
     };
   }