diff --git a/configs/flake-parts/dev.nix b/configs/flake-parts/dev.nix
index ab20fb8a..201231a6 100644
--- a/configs/flake-parts/dev.nix
+++ b/configs/flake-parts/dev.nix
@@ -31,7 +31,14 @@
     # more preferable than installing all of the packages at the system
     # configuration (or even home environment).
     devShells = import ../../shells { inherit pkgs; } // {
-      default = import ../../shell.nix { inherit pkgs; };
+      default = import ../../shell.nix {
+        inherit pkgs;
+        extraPackages = with pkgs; [
+          # Mozilla addons-specific tooling. Unfortunately, only available with
+          # flakes-based setups.
+          nur.repos.rycee.mozilla-addons-to-nix
+        ];
+      };
       docs = import ../../docs/shell.nix { inherit pkgs; };
     };
   };
diff --git a/shell.nix b/shell.nix
index 9feb1a4b..cad00d03 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,4 +1,4 @@
-{ pkgs ? import <nixpkgs> { } }:
+{ pkgs ? import <nixpkgs> { }, extraPackages ? [ ] }:
 
 pkgs.mkShell {
   packages = with pkgs; [
@@ -26,8 +26,5 @@ pkgs.mkShell {
     stylua # ...for Lua.
     black # ...for Python.
     nixpkgs-fmt # ...for Nix.
-
-    # Mozilla addons-specific tooling.
-    nur.repos.rycee.mozilla-addons-to-nix
-  ];
+  ] ++ extraPackages;
 }