diff --git a/packages/playground/php-cors-proxy/cors-proxy.php b/packages/playground/php-cors-proxy/cors-proxy.php
index 4a7c8ee46e..12ad6db3fb 100644
--- a/packages/playground/php-cors-proxy/cors-proxy.php
+++ b/packages/playground/php-cors-proxy/cors-proxy.php
@@ -112,7 +112,7 @@
 $curlHeaders = kv_headers_to_curl_format(
     filter_headers_strings(
         getallheaders(),
-        $default_allowed_headers,
+        $headers_requiring_opt_in,
         $strictly_disallowed_headers
     )
 );