diff --git a/home/applications/firefox/default.nix b/home/applications/firefox/default.nix
index db2f0fc..e7e4b2c 100644
--- a/home/applications/firefox/default.nix
+++ b/home/applications/firefox/default.nix
@@ -1,19 +1,12 @@
 {pkgs, ...}: {
   programs.firefox = {
     enable = true;
-    profiles."default" = {
-      extraConfig = ''
-        ${builtins.readFile (pkgs.fetchurl {
-          # FIXME: IFD
-          url = "https://raw.githubusercontent.com/arkenfox/user.js/126.1/user.js";
-          hash = "sha256-XRtG0iLKh8uqbeX7Rc2H6VJwZYJoNZPBlAfZEfrSCP4=";
-        })}
-        ${builtins.readFile ./user-overrides.js}
-      '';
+    package = pkgs.firefox.overrides {
+      extraPrefsFiles = [
+        "${pkgs.arkenfox-userjs}/user.cfg"
+        ./user-overrides.js
+      ];
     };
-  };
-
-  home.sessionVariables = {
-    MOZ_USE_XINPUT2 = "1";
+    profiles."default" = {};
   };
 }
diff --git a/home/applications/thunderbird/default.nix b/home/applications/thunderbird/default.nix
index 5b7628d..5e33efc 100644
--- a/home/applications/thunderbird/default.nix
+++ b/home/applications/thunderbird/default.nix
@@ -1,16 +1,15 @@
 {pkgs, ...}: {
   programs.thunderbird = {
     enable = true;
-    profiles.default = {
-      isDefault = true;
-      extraConfig = ''
-        ${builtins.readFile (pkgs.fetchurl {
-          # FIXME: IFD
+    package = pkgs.thunderbird.override {
+      extraPerfFiles = [
+        (pkgs.fetchurl {
           url = "https://raw.githubusercontent.com/HorlogeSkynet/thunderbird-user.js/d6b18302e46349d9924c8a76951bae6efca51501/user.js";
           hash = "sha256-66B1yLQkQnydAUXD7KGt32OhWSYcdWX+BUozrgW9uAg=";
-        })}
-        ${builtins.readFile ./user-overrides.js}
-      '';
+        })
+        ./user-overrides.js
+      ];
     };
+    profiles.default.isDefault = true;
   };
 }