diff --git a/flake.nix b/flake.nix
index e62c252..96a0973 100644
--- a/flake.nix
+++ b/flake.nix
@@ -3,17 +3,17 @@
 
   nixConfig = {
     extra-substituters = [
+      "https://cache.rgbcu.be/"
       "https://cache.garnix.io/"
       "https://cache.privatevoid.net"
-      "https://cache.rgbcu.be/"
       "https://hyprland.cachix.org/"
       "https://nix-community.cachix.org/"
     ];
 
     extra-trusted-public-keys = [
+      "cache.rgbcu.be:nBN/5Qg5E8GIYwaoslm9DYo2zeqlBiCVNCPf17djr+w="
       "cache.garnix.io:CTFPyKSLcx5RMJKfLo5EEPUObbA78b0YQ2DTCJXqr9g="
       "cache.privatevoid.net:SErQ8bvNWANeAvtsOESUwVYr2VJynfuc9JRwlzTTkVg="
-      "cache.rgbcu.be:nBN/5Qg5E8GIYwaoslm9DYo2zeqlBiCVNCPf17djr+w="
       "hyprland.cachix.org-1:a7pgxzMz7+chwVL3/pzj6jIBMioiJM7ypFP8PwtkuGc="
       "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
     ];
diff --git a/modules/common/helix.nix b/modules/common/helix.nix
index d13e06f..edc08eb 100644
--- a/modules/common/helix.nix
+++ b/modules/common/helix.nix
@@ -209,7 +209,7 @@ in {
       lua-language-server
 
       # MARKDOWN
-      marksman
+      markdown-oxide
 
       # NIX
       nixfmt-rfc-style
diff --git a/modules/common/nix.nix b/modules/common/nix.nix
index bc60bb7..a5ca627 100644
--- a/modules/common/nix.nix
+++ b/modules/common/nix.nix
@@ -42,14 +42,14 @@ in {
     |> mapAttrs (_: flake: { inherit flake; });
 
   nix.settings = (import <| self + /flake.nix).nixConfig
-    |> flip removeAttrs (optionals config.isDarwin [ "use-cgroups" ])
-    |> (if config.isLinux && config.services.nix-serve.enable then
-      (cfg: cfg // {
-        extra-substituters = cfg.extra-substituters
-          |> filter (x: match ".*cache.rgbcu.be.*" x != null);
-      })
-    else
-      id);
+    |> flip removeAttrs (optionals config.isDarwin [ "use-cgroups" ]);
+    # |> (if config.isLinux && config.services.nix-serve.enable then
+    #   (cfg: cfg // {
+    #     extra-substituters = cfg.extra-substituters
+    #       |> filter (x: match ".*cache.rgbcu.be.*" x == null);
+    #   })
+    # else
+    #   id);
 
   nix.optimise.automatic = true;
 
diff --git a/modules/common/nushell/default.nix b/modules/common/nushell/default.nix
index c36f193..8e8005a 100644
--- a/modules/common/nushell/default.nix
+++ b/modules/common/nushell/default.nix
@@ -57,6 +57,11 @@ in {
         inherit (self.starship) src;
         hash = "sha256-nH1iYjKw/GbYKadoymH3onWBbMzuMUaRCSTNWVE+A9E=";
       };
+
+      nativeBuildInputs = old.nativeBuildInputs ++ [
+        pkgs.cmake
+        pkgs.zlib-ng
+      ];
     });
   })];
 
diff --git a/modules/darwin/paperwm.nix b/modules/darwin/paperwm.nix
index 070f035..bff5a14 100644
--- a/modules/darwin/paperwm.nix
+++ b/modules/darwin/paperwm.nix
@@ -18,7 +18,7 @@ in {
     NSScrollAnimationEnabled = true;
     NSWindowResizeTime       = 0.001;
 
-    # "com.apple.keyboard.fnState" = true; # Invert Fn.
+    "com.apple.keyboard.fnState" = false; # Don't invert Fn.
     "com.apple.trackpad.scaling" = 1.5;  # Faster mouse speed.
 
     InitialKeyRepeat             = 15;
diff --git a/modules/linux/kernel.nix b/modules/linux/kernel.nix
index 0ca1079..50976d1 100644
--- a/modules/linux/kernel.nix
+++ b/modules/linux/kernel.nix
@@ -1,5 +1,8 @@
-{ pkgs, ... }: {
-  boot.kernelPackages = pkgs.linuxPackages_latest;
+{ config, pkgs, ... }: {
+  boot.kernelPackages = if config.isServer then
+    pkgs.linuxPackages_latest
+  else
+    pkgs.linuxKernel.packages.linux_zen;
 
   # Credits:
   # - https://github.com/NotAShelf/nyx/blob/main/modules/core/common/system/security/kernel.nix