diff --git a/lib/types/multipart.js b/lib/types/multipart.js
index cc0d7bb..dfe7cd1 100644
--- a/lib/types/multipart.js
+++ b/lib/types/multipart.js
@@ -361,7 +361,9 @@ class Multipart extends Writable {
           this._fileStream,
           { filename,
             encoding: partEncoding,
-            mimeType: partType }
+            mimeType: partType,
+            header
+          }
         );
       } else {
         // Non-file