diff --git a/flake.nix b/flake.nix
index e7053c4..7449fd2 100644
--- a/flake.nix
+++ b/flake.nix
@@ -41,11 +41,21 @@
     eachDefaultSystem
       (system:
       let
+        inherit (nixpkgs) lib;
         pkgs = import nixpkgs {
           inherit system;
           overlays = [ self.overlays.default ];
         };
 
+        # FIXME: does it pickup the parser correctly?
+        nvim-test = pkgs.writeShellScriptBin "nvim-test" ''
+          export NVIM_PLENARY='${pkgs.vimPlugins.plenary-nvim}'
+          export NVIM_TREESITTER='${pkgs.vimPlugins.nvim-treesitter}'
+
+          ${pkgs.neovim}/bin/nvim --headless --noplugin -u scripts/minimal_init.lua \
+              -c "PlenaryBustedDirectory test/ { minimal_init = '${./scripts/minimal_init.lua}' }"
+        '';
+
         bump-version = pkgs.writeShellScriptBin "bump-version" ''
           set -eu
 
@@ -90,6 +100,13 @@
                 enable = true;
               };
 
+              nvim-test = {
+                enable = true;
+                name = "nvim tests";
+                entry = "${lib.getExe nvim-test}";
+                pass_filenames = false;
+              };
+
               tree-sitter = {
                 enable = true;
                 name = "tree-sitter tests";
@@ -112,6 +129,7 @@
             nativeBuildInputs = with pkgs; [
               bump-version
               nodejs
+              nvim-test
               # FIXME: waiting on #301336
               # (tree-sitter.override { webUISupport = true; })
               tree-sitter
diff --git a/queries/highlights.scm b/queries/highlights.scm
index b4cc660..7422e6f 100644
--- a/queries/highlights.scm
+++ b/queries/highlights.scm
@@ -49,6 +49,14 @@
     field: (identifier) @variable.member))
 ; }}}
 
+; Built-ins {{{
+[
+ (unset)
+ "default"
+] @variable.builtin
+(selection_type) @function.builtin
+; }}}
+
 ; Expressions {{{
 (map_expression
   (property
diff --git a/scripts/minimal_init.lua b/scripts/minimal_init.lua
new file mode 100644
index 0000000..d43d3dc
--- /dev/null
+++ b/scripts/minimal_init.lua
@@ -0,0 +1,19 @@
+vim.opt.runtimepath:append(os.getenv("NVIM_PLENARY"))
+vim.opt.runtimepath:append(os.getenv("NVIM_TREESITTER"))
+
+vim.cmd.runtime({ "plugin/plenary.vim", bang = true })
+vim.cmd.runtime({ "plugin/nvim-treesitter.lua", bang = true })
+
+vim.filetype.add({
+  extension = {
+    bp = "bp",
+  },
+})
+
+vim.o.swapfile = false
+vim.bo.swapfile = false
+
+require("nvim-treesitter.configs").setup({
+  indent = { enable = true },
+  highlight = { enable = true },
+})
diff --git a/test/highlight/builtins.bp b/test/highlight/builtins.bp
new file mode 100644
index 0000000..508a8ed
--- /dev/null
+++ b/test/highlight/builtins.bp
@@ -0,0 +1,14 @@
+foo = select(soong_config_variable("my_namespace", "my_var"), {
+    //       ^ function.builtin
+    "foo": unset,
+    //     ^ variable.builtin
+    default: select(variant("VARIANT") {}),
+    // <- variable.builtin
+    //              ^ function.builtin
+})
+
+/* Assigning to builtins is conveniently not allowed at runtime */
+unset = 12
+// <- variable.builtin
+default = 27
+// <- variable.builtin