diff --git a/tests/repo/mod.rs b/tests/repo/mod.rs
index 10b48f3211..0c61f4abef 100644
--- a/tests/repo/mod.rs
+++ b/tests/repo/mod.rs
@@ -17,8 +17,12 @@ const REVISION: &str = "9f5fc1bd443f59583e7af0d94d289f95fe1e20c4";
 
 #[rustfmt::skip]
 static EXCLUDE_FILES: &[&str] = &[
-    // TODO
+    // TODO: anonymous union and struct
+    // https://github.com/dtolnay/syn/issues/1049
     "src/tools/rustfmt/tests/target/anonymous-types.rs",
+
+    // TODO: generic const items
+    // https://github.com/dtolnay/syn/issues/1497
     "tests/rustdoc/generic-const-items.rs",
     "tests/rustdoc/inline_cross/auxiliary/generic-const-items.rs",
     "tests/ui/generic-const-items/associated-const-equality.rs",