diff --git a/composer-require-checker.json b/composer-require-checker.json
index 67d664d..7a40ab4 100644
--- a/composer-require-checker.json
+++ b/composer-require-checker.json
@@ -33,6 +33,7 @@
         "Composer\\InstalledVersions",
         "GuzzleHttp\\Psr7\\HttpFactory",
         "GuzzleHttp\\Psr7\\Message",
+        "GuzzleHttp\\Psr7\\MultipartStream",
         "GuzzleHttp\\Psr7\\Response",
         "GuzzleHttp\\Psr7\\Utils",
         "Illuminate\\Support\\Collection",
diff --git a/src/Foundation/Message.php b/src/Foundation/Message.php
index 28efb1d..860732a 100644
--- a/src/Foundation/Message.php
+++ b/src/Foundation/Message.php
@@ -90,6 +90,9 @@ protected function toQuery(
         return http_build_query($this->toPayload(), $numericPrefix, $argSeparator, $encodingType);
     }
 
+    /**
+     * @psalm-suppress UndefinedConstant
+     */
     protected function toMultipart(int $options = MULTIPART_TRY_OPEN_FILE): MultipartStream
     {
         return new MultipartStream(Utils::multipartFor($this->toPayload(), $options));