diff --git a/functions/codeblock/src/index.ts b/functions/codeblock/src/index.ts
index b3af3d3..0123832 100644
--- a/functions/codeblock/src/index.ts
+++ b/functions/codeblock/src/index.ts
@@ -67,6 +67,16 @@ export function handler({
 
 export default {
   async fetch(request: Request): Promise<Response> {
+    if (request.method === "OPTIONS") {
+      return new Response("", {
+        headers: {
+          "Access-Control-Allow-Origin": "*",
+          "Access-Control-Allow-Methods": "POST",
+          "Access-Control-Allow-Headers": "Content-Type",
+        },
+      });
+    }
+
     const message = await request.json<Message>();
     const response = handler(message);
 
@@ -74,6 +84,9 @@ export default {
       status: response.statusCode,
       headers: {
         "Content-Type": "application/json",
+        "Access-Control-Allow-Origin": "*",
+        "Access-Control-Allow-Methods": "POST",
+        "Access-Control-Allow-Headers": "Content-Type",
       },
     });
   },