diff --git a/htdocs/install/mysql/tables/llx_payment_salary.sql b/htdocs/install/mysql/tables/llx_payment_salary.sql
index c56e6459aa0..0c19ee93915 100644
--- a/htdocs/install/mysql/tables/llx_payment_salary.sql
+++ b/htdocs/install/mysql/tables/llx_payment_salary.sql
@@ -19,7 +19,7 @@
 create table llx_payment_salary
 (
   rowid           integer AUTO_INCREMENT PRIMARY KEY,
-  ref             varchar(30) NOT NULL,       -- payment reference number
+  ref             varchar(30) NULL,           -- payment reference number (currently NULL because there is no numbering manager yet)
   tms             timestamp,
   datec           datetime,                   -- Create date
   fk_user         integer NOT NULL,
diff --git a/htdocs/install/mysql/tables/llx_payment_various.sql b/htdocs/install/mysql/tables/llx_payment_various.sql
index d3351287e58..023d6d018a7 100644
--- a/htdocs/install/mysql/tables/llx_payment_various.sql
+++ b/htdocs/install/mysql/tables/llx_payment_various.sql
@@ -19,7 +19,7 @@
 create table llx_payment_various
 (
   rowid                 integer AUTO_INCREMENT PRIMARY KEY,
-  ref                   varchar(30) NOT NULL,       -- payment reference number
+  ref                   varchar(30) NULL,           -- payment reference number (currently NULL because there is no numbering manager yet)
   num_payment           varchar(50),				-- num cheque or other
   label                 varchar(255),
   tms                   timestamp,