diff --git a/drizzle/0001_add_checkin_type.sql b/drizzle/0001_add_checkin_type.sql
index 4ae2e1b..7255e32 100644
--- a/drizzle/0001_add_checkin_type.sql
+++ b/drizzle/0001_add_checkin_type.sql
@@ -1,2 +1,3 @@
 ALTER TABLE `progress` ADD `checkin_type` text NOT NULL DEFAULT 'normal';
 ALTER TABLE `progress` ADD `checked_at` text NOT NULL DEFAULT '';
+-- New check-ins populate checked_at in the application layer.