diff --git a/configuration.nix b/configuration.nix
index 1eb986d..4e6cb33 100644
--- a/configuration.nix
+++ b/configuration.nix
@@ -16,6 +16,7 @@
     ];
   };
 
+  system.stateVersion = "25.05";   # ← einmalig festnageln
   services.openssh.enable = true;
   services.zfs.autoScrub.enable = true;   # Snapshots & Details kommen später
 
@@ -23,4 +24,5 @@
   boot.kernelPackages = pkgs.linuxPackages_6_12;
 
   environment.systemPackages = with pkgs; [ git vim ];
+
 }