diff --git a/Formula/rpcgen.rb b/Formula/rpcgen.rb
index 7320f424421..7ade36be11c 100644
--- a/Formula/rpcgen.rb
+++ b/Formula/rpcgen.rb
@@ -3,6 +3,7 @@ class Rpcgen < Formula
   homepage "https://opensource.apple.com/"
   url "https://opensource.apple.com/tarballs/developer_cmds/developer_cmds-66.tar.gz"
   sha256 "99d6c4ef4f32593df937a42d50400c17054247e875ab8cfb3bf0f2de19a90860"
+  # Sun-RPC license issue, https://github.com/spdx/license-list-XML/issues/906
 
   bottle do
     cellar :any_skip_relocation