system?

flake.lock

@@ -2,14 +2,18 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 0,
+        "lastModified": 1719254875,
         "narHash": "sha256-ECni+IkwXjusHsm9Sexdtq8weAq/yUyt1TWIemXt3Ko=",
-        "path": "/nix/store/bi5zxc0v5g6ylygdwyqzh280sccg3ykb-source",
-        "type": "path"
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "2893f56de08021cffd9b6b6dfc70fd9ccd51eb60",
+        "type": "github"
       },
       "original": {
-        "id": "nixpkgs",
-        "type": "indirect"
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
       }
     },
     "root": {

flake.nix

@@ -8,6 +8,7 @@
           name = "backgrounds";
           builder = "${nixpkgs.bash}/bin/bash";
           args = [ ./builder.sh ];
+          system = builtins.currentSystem;
         };
     };
 }