diff --git a/docs/building.md b/docs/building.md
index 667e8ad..1b5cd1a 100644
--- a/docs/building.md
+++ b/docs/building.md
@@ -58,4 +58,6 @@ cmake --install build
 `PATH_MAX` and `NULL` are used unconditionally but only included under the
 stdlib branch, so the header's includes need untangling before
 `-DAKERR_USE_STDLIB=OFF` builds. The list above still states what a replacement
-must provide. See [TODO.md](../TODO.md).
+must provide. That configuration does not currently compile -- `bool`, `PATH_MAX` and `NULL`
+are used unconditionally but included only under the stdlib branch. See
+[issue #12](https://source.starfort.tech/andrew/libakerror/issues/12).