diff --git a/doc/sdk/http-transformation-plugin/sample-buffered-null-transformation-plugin.en.rst b/doc/sdk/http-transformation-plugin/sample-buffered-null-transformation-plugin.en.rst
index 866eb61aaa7..f1e1b3ade54 100644
--- a/doc/sdk/http-transformation-plugin/sample-buffered-null-transformation-plugin.en.rst
+++ b/doc/sdk/http-transformation-plugin/sample-buffered-null-transformation-plugin.en.rst
@@ -193,11 +193,11 @@ transform:
 #. The ``handle_output`` function writes the buffer to the output
    vconnection:
 
-.. code-block:: c
+   .. code-block:: c
 
-   data->output_vio =
-      TSVConnWrite (output_conn, contp, data->output_reader,
-      TSIOBufferReaderAvail (data->output_reader) );
+      data->output_vio =
+         TSVConnWrite (output_conn, contp, data->output_reader,
+         TSIOBufferReaderAvail (data->output_reader) );
 
    The following diagram illustrates the write to the output
    vconnection: