diff --git a/grammar.js b/grammar.js
index 86d0dd6..d0cee14 100644
--- a/grammar.js
+++ b/grammar.js
@@ -118,6 +118,7 @@ module.exports = grammar({
       ),
     )),
 
+    // FIXME
     select_expression: ($) => seq(
       "select",
       "(",
@@ -127,6 +128,7 @@ module.exports = grammar({
       ")",
     ),
 
+    // FIXME
     select_value: ($) => seq(
       field("type", alias(
         choice("product_variable", "release_variable", "variant"),
@@ -137,6 +139,7 @@ module.exports = grammar({
       ")",
     ),
 
+    // FIXME
     soong_config_variable: ($) => seq(
       field("type", alias("soong_config_variable", $.selection_type)),
       "(",
@@ -151,6 +154,9 @@ module.exports = grammar({
       ")",
     ),
 
+    // FIXME
+    // FIXME: keyword.conditional or keyword.directive for 'select'
+    // FIXME: builtin for unset and default?
     select_cases: ($) => seq(
       "{",
       optional(trailingCommaSeparated($.select_case)),
@@ -159,12 +165,14 @@ module.exports = grammar({
       "}",
     ),
 
+    // FIXME
     select_case: ($) => seq(
       field("pattern", $._string_literal),
       ":",
       field("value", $._case_value)
     ),
 
+    // FIXME
     default_case: ($) => seq(
       field("pattern", "default"),
       ":",
diff --git a/queries/highlights.scm b/queries/highlights.scm
index a28d844..fa87c49 100644
--- a/queries/highlights.scm
+++ b/queries/highlights.scm
@@ -49,6 +49,15 @@
     field: (identifier) @variable.member))
 ; }}}
 
+; Built-ins {{{
+[
+ (unset)
+ "default"
+] @variable.builtin
+
+(selection_type) @function.builtin
+; }}}
+
 ; Expressions {{{
 (map_expression
   (property