diff --git a/src/Control/HTTPRequest.php b/src/Control/HTTPRequest.php
index c3d5da5e7..56680464b 100644
--- a/src/Control/HTTPRequest.php
+++ b/src/Control/HTTPRequest.php
@@ -468,6 +468,8 @@ class HTTPRequest implements ArrayAccess
      * Construct an HTTPResponse that will deliver a file to the client.
      * Caution: Since it requires $fileData to be passed as binary data (no stream support),
      * it's only advisable to send small files through this method.
+     * This function needs to be called inside the controller’s response, e.g.:
+     * <code>$this->setResponse(HTTPRequest::send_file('the content', 'filename.txt'));</code>
      *
      * @static
      * @param $fileData