diff --git a/ixx/src/action/index.rs b/ixx/src/action/index.rs
index fcd27ab..2e20132 100644
--- a/ixx/src/action/index.rs
+++ b/ixx/src/action/index.rs
@@ -39,6 +39,7 @@ pub(crate) fn index(module: IndexModule) -> anyhow::Result<()> {
     let options: HashMap<String, option::Option> = serde_json::from_reader(file)?;
 
     for (name, option) in options {
+      // internal options which cannot be hidden when importing existing options.json
       if name == "_modules.args" {
         continue;
       }