diff --git a/data/hostname/worker01.softwareheritage.org.yaml b/data/hostname/worker01.softwareheritage.org.yaml
index e8f393c3..1a9ae2e9 100644
--- a/data/hostname/worker01.softwareheritage.org.yaml
+++ b/data/hostname/worker01.softwareheritage.org.yaml
@@ -1,28 +1,29 @@
 networks:
   private:
     interface: ens19
     address: 192.168.100.21
     netmask: 255.255.255.0
     gateway: 192.168.100.1
   default:
     interface: ens18
     address: 128.93.193.21
     netmask: 255.255.255.0
     gateway: 128.93.193.254
 
+swh::deploy::worker::lister::concurrency: 1
 swh::deploy::worker::lister::config:
   storage: "%{alias('swh::remote_service::storage::config::writable')}"
   scheduler: "%{alias('swh::remote_service::scheduler::config::writable')}"
   lister:
     cls: local
     args:
       db: "postgresql://%{hiera('swh::deploy::worker::lister::db::user')}:%{hiera('swh::deploy::lister::db::password')}@%{hiera('swh::deploy::worker::lister::db::host')}:%{hiera('swh::deploy::worker::lister::db::port')}/%{hiera('swh::deploy::worker::lister::db::name')}"
   celery:
     task_broker: "%{alias('swh::deploy::worker::task_broker')}"
     task_queues:
       - swh.lister.github.tasks.IncrementalGitHubLister
       - swh.lister.github.tasks.RangeGitHubLister
       - swh.lister.github.tasks.FullGitHubRelister
 
   credentials: "%{alias('swh::deploy::worker::lister::config::credentials')}"