diff --git a/applications/ldap/client.nix b/applications/ldap/client.nix
index 32ce8da..d172b42 100644
--- a/applications/ldap/client.nix
+++ b/applications/ldap/client.nix
@@ -69,11 +69,6 @@ in {
       }
     ];
 
-    nix.settings.trusted-users = [
-      "root"
-      "@skynet-admins-linux"
-    ];
-
     # give users a home dir
     security.pam.services.sshd.makeHomeDir = true;
 
diff --git a/machines/_base.nix b/machines/_base.nix
index d3425a6..240bf59 100644
--- a/machines/_base.nix
+++ b/machines/_base.nix
@@ -25,8 +25,27 @@
     ../applications/restic.nix
   ];
 
-  # flakes are essensial
-  nix.settings.experimental-features = ["nix-command" "flakes"];
+  nix = {
+    settings = {
+      # flakes are essensial
+      experimental-features = ["nix-command" "flakes"];
+      trusted-users = [
+        "root"
+        "@skynet-admins-linux"
+      ];
+    };
+
+    # https://nixos.wiki/wiki/Storage_optimization
+    gc = {
+      automatic = true;
+      dates = "weekly";
+      options = "--delete-older-than 30d";
+    };
+    extraOptions = ''
+      min-free = ${toString (100 * 1024 * 1024)}
+      max-free = ${toString (1024 * 1024 * 1024)}
+    '';
+  };
 
   system.stateVersion = "22.11";