diff --git a/htdocs/install/mysql/migration/12.0.0-13.0.0.sql b/htdocs/install/mysql/migration/12.0.0-13.0.0.sql
index 1a42a065af4..ec0abb5f597 100644
--- a/htdocs/install/mysql/migration/12.0.0-13.0.0.sql
+++ b/htdocs/install/mysql/migration/12.0.0-13.0.0.sql
@@ -59,8 +59,9 @@ ALTER TABLE llx_mrp_mo_extrafields ADD INDEX idx_mrp_mo_fk_object(fk_object);
 
 -- For v13
 -- members
-ALTER TABLE llx_adherent ADD COLUMN ref varchar(30) NOT NULL AFTER rowid;
-UPDATE llx_adherent SET ref=rowid WHERE ref = '';
+ALTER TABLE llx_adherent ADD COLUMN ref varchar(30) AFTER rowid;
+UPDATE llx_adherent SET ref = rowid WHERE ref = '';
+ALTER TABLE llx_adherent MODIFY COLUMN ref varchar(30) NOT NULL;
 ALTER TABLE llx_adherent ADD UNIQUE INDEX uk_adherent_ref (ref, entity);
 
 ALTER TABLE llx_bom_bom ADD COLUMN bomtype integer DEFAULT 0;