diff --git a/include/clap/ext/draft/undo.h b/include/clap/ext/draft/undo.h
index 0dedcdca..c84e9608 100644
--- a/include/clap/ext/draft/undo.h
+++ b/include/clap/ext/draft/undo.h
@@ -102,7 +102,7 @@ typedef struct clap_plugin_undo_delta {
 typedef struct clap_plugin_undo_context {
    // Indicate if it is currently possible to perform a redo or undo operation.
    // if can_* is false then it invalidates the corresponding name.
-   // [main-thread]
+   // [main-thread & plugin-subscribed-to-undo-context]
    void(CLAP_ABI *set_can_undo)(const clap_plugin_t *plugin, bool can_undo);
    void(CLAP_ABI *set_can_redo)(const clap_plugin_t *plugin, bool can_redo);