diff --git a/src/Decorator/StreamDecorator.php b/src/Decorator/StreamDecorator.php
index b1f306d..5a6bb2d 100644
--- a/src/Decorator/StreamDecorator.php
+++ b/src/Decorator/StreamDecorator.php
@@ -86,6 +86,9 @@ public function getContents(): string
         return $this->stream->getContents();
     }
 
+    /**
+     * @return mixed
+     */
     public function getMetadata(string $key = null)
     {
         return $this->stream->getMetadata($key);