diff --git a/content/blog/13_compiler_cleanup/index.md b/content/blog/13_compiler_cleanup/index.md
index f43bef1..72d56a8 100644
--- a/content/blog/13_compiler_cleanup/index.md
+++ b/content/blog/13_compiler_cleanup/index.md
@@ -866,3 +866,7 @@ name with `f_`, much like `create_custom_function`:
 I think that's enough. If we chose to turn more compiler
 data structures into classes, I think we would've quickly drowned
 in one-line getter and setter methods.
+
+{{< todo >}}
+Assertion failure on `set_mangled_name` on non-existent function,
+too. {{< /todo >}}