diff --git a/src/index.php b/src/index.php
index 1939977..a3adac5 100644
--- a/src/index.php
+++ b/src/index.php
@@ -20,7 +20,7 @@ echo $response->getHeaderLine('content-type') . PHP_EOL;
 echo $response->getBody() . PHP_EOL;
 
 // asynchronous
-$request = new Request('GET', 'https://httpbin.org');
+$request = new Request('GET', 'http://httpbin.org');
 
 $promise = $client
     ->sendAsync($request)