diff --git a/TODO b/TODO
index dc1eae391c..68645c0c4c 100644
--- a/TODO
+++ b/TODO
@@ -20,7 +20,7 @@ Janitorial Clean-ups:
 Features:
 
 * cryptsetup/homed: also support FIDO2 HMAC password logic for unlocking
-  devices.
+  devices. (see: https://github.com/mjec/fido2-hmac-secret)
 
 * systemd-gpt-auto should probably set x-systemd.growfs on the mounts it
   creates