diff --git a/hosts/backup-4/backup.nix b/hosts/backup-4/backup.nix
new file mode 100644
index 0000000..f497e71
--- /dev/null
+++ b/hosts/backup-4/backup.nix
@@ -0,0 +1,13 @@
+{ ... }:
+
+{
+  services.borgbackup.repos = {
+    krypton = {
+      authorizedKeys = [ "ssh-rsa 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 clerie@krypton" ];
+      path = "/mnt/backup-4/krypton";
+    };
+  };
+
+  # fix borgbackup primary grouping
+  users.users.borg.group = "borg";
+}
diff --git a/hosts/backup-4/configuration.nix b/hosts/backup-4/configuration.nix
index 1883203..6b66b13 100644
--- a/hosts/backup-4/configuration.nix
+++ b/hosts/backup-4/configuration.nix
@@ -5,6 +5,8 @@
     [
       ./hardware-configuration.nix
       ../../configuration/proxmox-vm
+
+      ./backup.nix
     ];
 
   boot.loader.grub.enable = true;