diff --git a/index.php b/index.php
index f605f3e..8a926c2 100644
--- a/index.php
+++ b/index.php
@@ -44,7 +44,7 @@ if (isset($_GET['secret']) && $_GET['secret'] === REGISTRATION_PASSWORD) {
     # send admin message
     $ch = curl_init();
     curl_setopt($ch, CURLOPT_URL, SYNAPSE_URL.'/_matrix/client/v3/rooms/'.ROOM_ID.'/send/m.room.message/'.filter_var($_POST['nonce'], FILTER_SANITIZE_FULL_SPECIAL_CHARS));
-    curl_setopt($ch, CURLOPT_PUT, true);
+    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'PUT');
     curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode([
         'body' => '@'.$username.':imninja.net just registered',
         'msgtype' => 'm.text'