diff --git a/htdocs/install/mysql/tables/llx_c_departements.key.sql b/htdocs/install/mysql/tables/llx_c_departements.key.sql
index 427d031a705..66194440610 100644
--- a/htdocs/install/mysql/tables/llx_c_departements.key.sql
+++ b/htdocs/install/mysql/tables/llx_c_departements.key.sql
@@ -21,5 +21,8 @@ ALTER TABLE llx_c_departements ADD UNIQUE uk_departements (code_departement,fk_r
 
 ALTER TABLE llx_c_departements ADD INDEX idx_departements_fk_region (fk_region);
 
+-- NOTE: We duplicate creation of unique keys on llx_c_regions NOW to be able to create foreign keys. 
+ALTER TABLE llx_c_regions ADD UNIQUE INDEX uk_code_region (code_region);
+
 ALTER TABLE llx_c_departements ADD CONSTRAINT fk_departements_fk_region	FOREIGN KEY (fk_region) REFERENCES llx_c_regions (code_region);