diff --git a/composer.json b/composer.json
index 394d7e2..604c2ab 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,8 @@
         "php": ">=5.4",
         "evenement/evenement": "^3.0 || ^2.0",
         "react/event-loop": "^1.2",
-        "react/http": "^1.6"
+        "react/http": "^1.6",
+        "react/promise": "^3 || ^2.10 || ^1.2.1"
     },
     "require-dev": {
         "phpunit/phpunit": "^9.6 || ^5.7 || ^4.8.35"
diff --git a/src/EventSource.php b/src/EventSource.php
index dbfd22e..58e32dc 100644
--- a/src/EventSource.php
+++ b/src/EventSource.php
@@ -270,6 +270,8 @@ public function close()
 
             $request->then(function (ResponseInterface $response) {
                 $response->getBody()->close();
+            }, function () {
+                // ignore to avoid reporting unhandled rejection
             });
             $request->cancel();
         }