diff --git a/addons/repair/models/repair.py b/addons/repair/models/repair.py
index 3a1fe59b63c..0e4cb922cc8 100644
--- a/addons/repair/models/repair.py
+++ b/addons/repair/models/repair.py
@@ -199,6 +199,8 @@ class Repair(models.Model):
 
     def action_validate(self):
         self.ensure_one()
+        if self.filtered(lambda repair: any(op.product_uom_qty < 0 for op in repair.operations)):
+            raise UserError(_("You can not enter negative quantities."))
         if self.product_id.type == 'consu':
             return self.action_repair_confirm()
         precision = self.env['decimal.precision'].precision_get('Product Unit of Measure')