diff --git a/runbot/controllers/frontend.py b/runbot/controllers/frontend.py
index 6954afd7..a115e537 100644
--- a/runbot/controllers/frontend.py
+++ b/runbot/controllers/frontend.py
@@ -495,6 +495,8 @@ class Runbot(Controller):
             limit -= len(builds)
 
         builds |= builds.search(builds_domain, order='id desc', limit=limit)
+        if not builds:
+            return {}
 
         builds = builds.search([('id', 'child_of', builds.ids)])
 
@@ -502,7 +504,8 @@ class Runbot(Controller):
         request.env.cr.execute("SELECT build_id, values FROM runbot_build_stat WHERE build_id IN %s AND category = %s", [tuple(builds.ids), key_category]) # read manually is way faster than using orm
         res = {}
         for (build_id, values) in request.env.cr.fetchall():
-            res.setdefault(parents[build_id], {}).update(values)
+            if values:
+                res.setdefault(parents[build_id], {}).update(values)
             # we need to update here to manage the post install case: we want to combine stats from all post_install childrens.
         return res