diff --git a/src/Network/Http/FormData/Part.php b/src/Network/Http/FormData/Part.php
index 12c103318f3..a888aed3f86 100644
--- a/src/Network/Http/FormData/Part.php
+++ b/src/Network/Http/FormData/Part.php
@@ -112,7 +112,7 @@ public function disposition($disposition = null)
     public function contentId($id = null)
     {
         if ($id === null) {
-            return $this->_contentId = $id;
+            return $this->_contentId;
         }
         $this->_contentId = $id;
     }