diff --git a/src/keyring_op.hpp b/src/keyring_op.hpp
index d61034064311e1f7367b88825104e26b6dbf2f05..1a295835cdfa2ede368be081555df8d24fa69982 100644
--- a/src/keyring_op.hpp
+++ b/src/keyring_op.hpp
@@ -6,6 +6,8 @@
 #include <gmodule.h>
 #include <rlib/stdio.hpp>
 
+// TODO: read https://gnome.pages.gitlab.gnome.org/libsecret/class.Service.html
+//       https://gnome.pages.gitlab.gnome.org/libsecret/method.Service.prompt.html
 inline std::string do_unlock_2(std::string keyring, std::string password) {
     GError *err = NULL;
     SecretService *service_proxy_ptr = secret_service_get_sync(SECRET_SERVICE_LOAD_COLLECTIONS, NULL, &err);