diff --git a/src/app.ts b/src/app.ts
index 10793de..fc51d1e 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -57,7 +57,7 @@ function generateLocationEndpoint(
   router.options(currentUrlEnpoint, (context) => {
     const allowedRequestHeaders = ["application/json"];
     if (location.image) allowedRequestHeaders.push("image/jpeg");
-    context.response.body = allowedRequestHeaders.join(",");
+    context.response.headers.set("Allow", allowedRequestHeaders.join(","));
   });
 
   if (location.input && location.input_response) {