diff --git a/hosts/focalor/default.nix b/hosts/focalor/default.nix
index 509f6b8..3a3eebd 100644
--- a/hosts/focalor/default.nix
+++ b/hosts/focalor/default.nix
@@ -51,7 +51,10 @@ in
   };
   boot.kernel.sysctl."net.ipv4.ip_forward" = 1;
   nix.settings = {
-    trusted-users = lib.mkForce [ "root" ];
+    trusted-users = lib.mkForce [
+      "root"
+      "nixremote"
+    ];
     extra-platforms = [ "aarch64-linux" ];
     extra-substituters = [
       "https://noctalia.cachix.org"
diff --git a/hosts/focalor/modules/nix-builder.nix b/hosts/focalor/modules/nix-builder.nix
new file mode 100644
index 0000000..8f24e52
--- /dev/null
+++ b/hosts/focalor/modules/nix-builder.nix
@@ -0,0 +1,13 @@
+# Builds for valefar: its nix-daemon connects as nixremote with the key in valefar's /etc/nix/builder_ed25519
+# (see hosts/valefar/remote-builder.nix), so valefar's CPU stays free for bonsai.
+{
+  users.groups.nixremote = { };
+  users.users.nixremote = {
+    isSystemUser = true;
+    group = "nixremote";
+    useDefaultShell = true;
+    openssh.authorizedKeys.keys = [
+      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIHVC/SxLmrLMA9hs4l/x3Et7OSYFujYzPCTTipycOvnl valefar nix builder"
+    ];
+  };
+}
diff --git a/hosts/valefar/default.nix b/hosts/valefar/default.nix
index 4dfe6e7..b134e3c 100644
--- a/hosts/valefar/default.nix
+++ b/hosts/valefar/default.nix
@@ -22,6 +22,7 @@
     ./wg-mesh.nix
     ./bonsai.nix
     ./open-webui.nix
+    ./remote-builder.nix
     ./spindle.nix
   ];
 
diff --git a/hosts/valefar/remote-builder.nix b/hosts/valefar/remote-builder.nix
new file mode 100644
index 0000000..1d5f6df
--- /dev/null
+++ b/hosts/valefar/remote-builder.nix
@@ -0,0 +1,36 @@
+# Builds go to focalor (16 cores, same nixpkgs) so valefar's CPU stays free for bonsai. focalor dual-boots: when it
+# is on Windows the connection times out after 3 s and nix builds here as before.
+{
+  programs.ssh.extraConfig = ''
+    Host focalor-builder
+      HostName 10.0.0.43
+      User nixremote
+      IdentityFile /etc/nix/builder_ed25519
+      ConnectTimeout 3
+  '';
+  programs.ssh.knownHosts.focalor = {
+    hostNames = [
+      "focalor-builder"
+      "10.0.0.43"
+    ];
+    publicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIMc9KcnDJ10ZwivfADacqltLDHbIw/jawkGsN9HCUO+h";
+  };
+
+  nix = {
+    distributedBuilds = true;
+    buildMachines = [
+      {
+        hostName = "focalor-builder";
+        protocol = "ssh-ng";
+        system = "x86_64-linux";
+        maxJobs = 2;
+        speedFactor = 4;
+        supportedFeatures = [
+          "big-parallel"
+          "benchmark"
+        ];
+      }
+    ];
+    settings.builders-use-substitutes = true;
+  };
+}