diff --git a/addons/project_purchase/models/project.py b/addons/project_purchase/models/project.py
index 6bf9a462cea..7f7344eb350 100644
--- a/addons/project_purchase/models/project.py
+++ b/addons/project_purchase/models/project.py
@@ -11,8 +11,10 @@ class Project(models.Model):
 
     @api.depends('analytic_account_id')
     def _compute_purchase_orders_count(self):
+        if not self.analytic_account_id:
+            self.purchase_orders_count = 0
+            return
         purchase_orders_data = self.env['purchase.order.line']._read_group([
-            ('account_analytic_id', '!=', False),
             ('account_analytic_id', 'in', self.analytic_account_id.ids)
         ], ['account_analytic_id', 'order_id:count_distinct'], ['account_analytic_id'])
         mapped_data = dict([(data['account_analytic_id'][0], data['order_id']) for data in purchase_orders_data])