diff --git a/src/bin/gen.rs b/src/bin/gen.rs
index 4b8a5afecf..89609bd77e 100644
--- a/src/bin/gen.rs
+++ b/src/bin/gen.rs
@@ -51,8 +51,12 @@ impl Grammar {
             write!(acc, "    {},\n", scream(kind)).unwrap();
         }
         acc.push_str("\n");
-        acc.push_str("    TOMBSTONE = !0 - 1,\n");
-        acc.push_str("    EOF = !0,\n");
+        acc.push_str("    // Technical SyntaxKinds: they appear temporally during parsing,\n");
+        acc.push_str("    // but never end up in the final tree\n");
+        acc.push_str("    #[doc(hidden)]\n");
+        acc.push_str("    TOMBSTONE,\n");
+        acc.push_str("    #[doc(hidden)]\n");
+        acc.push_str("    EOF,\n");
         acc.push_str("}\n");
         acc.push_str("pub(crate) use self::SyntaxKind::*;\n");
         acc.push_str("\n");
diff --git a/src/syntax_kinds.rs b/src/syntax_kinds.rs
index aa19c2adff..cc9e74f8e8 100644
--- a/src/syntax_kinds.rs
+++ b/src/syntax_kinds.rs
@@ -92,8 +92,12 @@ pub enum SyntaxKind {
     ALIAS,
     VISIBILITY,
 
-    TOMBSTONE = !0 - 1,
-    EOF = !0,
+    // Technical SyntaxKinds: they appear temporally during parsing,
+    // but never end up in the final tree
+    #[doc(hidden)]
+    TOMBSTONE,
+    #[doc(hidden)]
+    EOF,
 }
 pub(crate) use self::SyntaxKind::*;