diff --git a/src/sql/upgrade-41.sql b/src/sql/upgrade-41.sql
index 509a5351..30784d96 100644
--- a/src/sql/upgrade-41.sql
+++ b/src/sql/upgrade-41.sql
@@ -2,4 +2,5 @@ create function notifyJobsetSharesChanged() returns trigger as 'begin notify job
 create trigger JobsetSharesChanged after update on Jobsets for each row
   when (old.schedulingShares != new.schedulingShares) execute procedure notifyJobsetSharesChanged();
 
+update Jobsets SET (schedulingShares) = (1) where NOT (schedulingShares > 0);
 alter table Jobsets add constraint jobsets_check check (schedulingShares > 0);