diff --git a/global/system-configuration.nix b/global/system-configuration.nix
index f70660f..999a3d3 100644
--- a/global/system-configuration.nix
+++ b/global/system-configuration.nix
@@ -56,31 +56,33 @@ in
     };
   };
 
-  nix.settings = {
-    auto-optimise-store = true;
-    experimental-features = [
-      "nix-command"
-      "flakes"
-    ];
+  nix = {
+    settings = {
+      auto-optimise-store = true;
+      experimental-features = [
+        "nix-command"
+        "flakes"
+      ];
 
-    substituters = [
-      "https://mirrors.ustc.edu.cn/nix-channels/store" # 中科大
-      "https://mirrors.tuna.tsinghua.edu.cn/nix-channels/store" # 清华
-      "https://mirrors.bfsu.edu.cn/nix-channels/store" # 北外
-      "https://mirror.sjtu.edu.cn/nix-channels/store" # 交大
-      "https://nixos-cn.cachix.org"
-      "https://cache.nixos.org/"
-    ];
+      substituters = [
+        "https://mirrors.ustc.edu.cn/nix-channels/store" # 中科大
+        "https://mirrors.tuna.tsinghua.edu.cn/nix-channels/store" # 清华
+        "https://mirrors.bfsu.edu.cn/nix-channels/store" # 北外
+        "https://mirror.sjtu.edu.cn/nix-channels/store" # 交大
+        "https://nixos-cn.cachix.org"
+        "https://cache.nixos.org/"
+      ];
 
-    trusted-users = [
-      "root"
-      "@wheel"
-    ];
-  };
+      trusted-users = [
+        "root"
+        "@wheel"
+      ];
+    };
 
-  nix.gc = {
-    automatic = true;
-    dates = "weekly";
-    options = "--delete-older-than 1w";
+    gc = {
+      automatic = true;
+      dates = "weekly";
+      options = "--delete-older-than 1w";
+    };
   };
 }