diff --git a/htdocs/install/mysql/migration/17.0.0-18.0.0.sql b/htdocs/install/mysql/migration/17.0.0-18.0.0.sql
index 64ede43cf9f..39772c45f77 100644
--- a/htdocs/install/mysql/migration/17.0.0-18.0.0.sql
+++ b/htdocs/install/mysql/migration/17.0.0-18.0.0.sql
@@ -411,3 +411,4 @@ CREATE TABLE llx_c_invoice_subtype (
 
 ALTER TABLE llx_c_invoice_subtype ADD UNIQUE INDEX uk_c_invoice_subtype (entity, code);
 
+ALTER TABLE llx_projet ADD COLUMN fk_project int DEFAULT NULL;
diff --git a/htdocs/install/mysql/tables/llx_projet.sql b/htdocs/install/mysql/tables/llx_projet.sql
index 531f0992f2c..8b4db824ca5 100644
--- a/htdocs/install/mysql/tables/llx_projet.sql
+++ b/htdocs/install/mysql/tables/llx_projet.sql
@@ -20,6 +20,7 @@
 create table llx_projet
 (
   rowid            	integer AUTO_INCREMENT PRIMARY KEY,
+  fk_project        integer DEFAULT NULL,       -- parent project rowid
   fk_soc           	integer,
   datec            	datetime,					-- date creation project
   tms              	timestamp DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,