diff --git a/migrations/0166.sql b/migrations/0166.sql
index 1d96118a..e1ff4e87 100644
--- a/migrations/0166.sql
+++ b/migrations/0166.sql
@@ -1,6 +1,7 @@
 UPDATE chores
 SET period_type = 'daily',
-period_interval = period_days
+period_interval = period_days,
+period_days = null
 WHERE period_type = 'dynamic-regular';
 
 DROP VIEW chores_current;