diff --git a/kubernetes/justfile b/kubernetes/justfile
index 8e45319..65aa836 100755
--- a/kubernetes/justfile
+++ b/kubernetes/justfile
@@ -10,7 +10,7 @@ KUBE_DIR := justfile_directory()
 TOFU := KUBE_DIR / "tofu"
 ANSIBLE := KUBE_DIR / "ansible"
 SSH_KEY := KUBE_DIR / "ssh-key"
-MASTER_IP := "192.168." + "`echo $((122 + ${CLUSTER_INDEX}))`" + ".10"
+MASTER_IP := "192.168." + `echo $((122 + ${CLUSTER_INDEX:-0}))` + ".10"
 
 # Build NixOS VM images
 build: