diff --git a/http_client.rst b/http_client.rst
index 9081ed4df4a..2f8c9eb0c13 100644
--- a/http_client.rst
+++ b/http_client.rst
@@ -627,6 +627,18 @@ according to the ``multipart/form-data`` content-type. The
         'body' => $formData->bodyToIterable(),
     ]);
 
+By default, :class:`Symfony\\Component\\Mime\\Part\\Multipart\\FormDataPart`
+will transfer file uploads in binary encoding. But you can enforce Base64::
+
+    $fileField = DataPart::fromPath(
+        path: '/path/to/uploaded/file',
+        encoding: 'base64'
+    );
+
+.. versionadded:: 6.3
+
+    The `encoding` parameter was introduced in Symfony 6.3.
+
 .. tip::
 
     When using multidimensional arrays the :class:`Symfony\\Component\\Mime\\Part\\Multipart\\FormDataPart`