diff --git a/ofborg/src/bin/mass-rebuilder.rs b/ofborg/src/bin/mass-rebuilder.rs
index 5d118c3..d35775b 100644
--- a/ofborg/src/bin/mass-rebuilder.rs
+++ b/ofborg/src/bin/mass-rebuilder.rs
@@ -35,7 +35,8 @@ fn main() -> Result<(), Box<dyn Error>> {
     let conn = easylapin::from_config(&cfg.rabbitmq)?;
     let mut chan = task::block_on(conn.create_channel())?;
 
-    let cloner = checkout::cached_cloner(Path::new(&cfg.checkout.root));
+    let root = Path::new(&cfg.checkout.root);
+    let cloner = checkout::cached_cloner(&root.join(cfg.runner.instance.to_string()));
     let nix = cfg.nix();
 
     let events = stats::RabbitMq::from_lapin(&cfg.whoami(), task::block_on(conn.create_channel())?);
diff --git a/ofborg/src/config.rs b/ofborg/src/config.rs
index c095cfe..dba6806 100644
--- a/ofborg/src/config.rs
+++ b/ofborg/src/config.rs
@@ -64,8 +64,14 @@ pub struct LogStorage {
     pub path: String,
 }
 
+const fn default_instance() -> u8 {
+    1
+}
+
 #[derive(Serialize, Deserialize, Debug)]
 pub struct RunnerConfig {
+    #[serde(default = "default_instance")]
+    pub instance: u8,
     pub identity: String,
     pub repos: Option<Vec<String>>,
     #[serde(default = "Default::default")]