diff --git a/src/markdown2/renderer.ml b/src/markdown2/renderer.ml
index f980e36085..99122f7d69 100644
--- a/src/markdown2/renderer.ml
+++ b/src/markdown2/renderer.ml
@@ -1,4 +1,6 @@
-(* This module is based on cmarkit (https://github.com/dbuenzli/cmarkit) which is distributed under the ISC License. *)
+(* Part of this code is:
+   Copyright (c) 2020 The cmarkit programmers. All rights reserved.
+   SPDX-License-Identifier: ISC *)
 
 let is_control = function '\x00' .. '\x1F' | '\x7F' -> true | _ -> false