diff --git a/hosts/x1g13/default.nix b/hosts/x1g13/default.nix
index 481a888..be9db17 100644
--- a/hosts/x1g13/default.nix
+++ b/hosts/x1g13/default.nix
@@ -7,4 +7,8 @@
 
   boot.initrd.luks.devices.cryptroot.device =
     "/dev/disk/by-partuuid/311d0f9c-f35f-42e6-b6fc-a4d67dd21b2e";
+
+  my.applications.git.homeManager = {
+    signingKey = "~/.ssh/id_ed25519_sk_rk.pub";
+  };
 }
diff --git a/modules/applications/arduino.nix b/modules/applications/arduino.nix
index 6117fed..2945d55 100644
--- a/modules/applications/arduino.nix
+++ b/modules/applications/arduino.nix
@@ -6,6 +6,14 @@
 }:
 let
   cfg = config.my.applications.arduino;
+  arduinoIdeX11 = pkgs.arduino-ide.overrideAttrs (old: {
+    nativeBuildInputs = (old.nativeBuildInputs or [ ]) ++ [ pkgs.makeWrapper ];
+
+    postFixup = (old.postFixup or "") + ''
+      wrapProgram $out/bin/arduino-ide \
+        --add-flags "--ozone-platform=x11"
+    '';
+  });
 in
 {
   options.my.applications.arduino = {
@@ -15,7 +23,7 @@ in
   config = lib.mkIf cfg.enable {
     environment.systemPackages = with pkgs; [
       arduino-cli # Arduino command-line interface
-      arduino-ide # Arduino IDE (GUI)
+      arduinoIdeX11 # Arduino IDE with X11 support
     ];
   };
 }
diff --git a/modules/applications/git/home.nix b/modules/applications/git/home.nix
index 18de309..9791d65 100644
--- a/modules/applications/git/home.nix
+++ b/modules/applications/git/home.nix
@@ -10,13 +10,28 @@ in
 {
   options.my.applications.git.homeManager = {
     enable = lib.mkEnableOption "git home-manager configuration";
+
+    signingKey = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = "~/.ssh/id_ed25519_sk_rk.pub";
+      example = "~/.ssh/id_ed25519.pub";
+      description = "SSH public key path used for Git commit and tag signing.";
+    };
   };
 
-  config.home-manager.sharedModules = [
-    {
-      config = lib.mkIf hmCfg.enable {
+  config = lib.mkIf hmCfg.enable {
+    assertions = [
+      {
+        assertion = hmCfg.signingKey != null;
+        message = "my.applications.git.homeManager.signingKey must be set per host.";
+      }
+    ];
+
+    home-manager.sharedModules = [
+      {
         programs.git = {
           enable = true;
+
           ignores = [
             ".direnv/"
             ".envrc"
@@ -24,12 +39,15 @@ in
           ];
 
           signing = {
+            key = hmCfg.signingKey;
+            format = "ssh";
             signByDefault = true;
           };
 
           settings = {
             user.name = cfg.userName;
             user.email = cfg.userEmail;
+
             push.default = "simple";
             credential.helper = "cache --timeout=7200";
             init.defaultBranch = "main";
@@ -37,16 +55,6 @@ in
             log.date = "iso";
             merge.conflictStyle = "diff3";
 
-            tag.gpgSign = true;
-
-            gpg = {
-              format = "ssh";
-
-              ssh = {
-                defaultKeyCommand = "ssh-add -L";
-              };
-            };
-
             alias = {
               br = "branch --sort=-committerdate";
               co = "checkout";
@@ -59,7 +67,7 @@ in
             };
           };
         };
-      };
-    }
-  ];
+      }
+    ];
+  };
 }