diff --git a/src/PushApi.php b/src/PushApi.php
index 265b737..6c92b9c 100644
--- a/src/PushApi.php
+++ b/src/PushApi.php
@@ -106,7 +106,7 @@ class PushApi
             }
         }
 
-        return $client->request('post', $url, [
+        return $client->request('POST', $url, [
             'multipart' => $multipart_form,
             'headers' => [
                 'Authorization' => 'Bearer ' . $this->api_key,