diff --git a/runbot/models/batch.py b/runbot/models/batch.py
index 0b3e40b7..2157aa24 100644
--- a/runbot/models/batch.py
+++ b/runbot/models/batch.py
@@ -92,7 +92,7 @@ class Batch(models.Model):
                 build = slot.build_id
                 if build.global_state in ('running', 'done'):
                     continue
-                testing_slots = build.slot_ids.filtered(lambda s: not s.skipped)
+                testing_slots = build.params_id.slot_ids.filtered(lambda s: not s.skipped)
                 if not testing_slots:
                     if build.global_state == 'pending':
                         build._skip('Newer build found')
diff --git a/runbot/models/build.py b/runbot/models/build.py
index 044d94e6..fa71d2e9 100644
--- a/runbot/models/build.py
+++ b/runbot/models/build.py
@@ -76,6 +76,8 @@ class BuildParameters(models.Model):
 
     fingerprint = fields.Char('Fingerprint', compute='_compute_fingerprint', store=True, index=True)
 
+    slot_ids = fields.One2many('runbot.batch.slot', 'params_id')
+
     _sql_constraints = [
         ('unique_fingerprint', 'unique (fingerprint)', 'avoid duplicate params'),
     ]