diff --git a/README.md b/README.md
index ba2bb01..e20877b 100644
--- a/README.md
+++ b/README.md
@@ -342,7 +342,8 @@ was a bit less important and if a core goal was finding latent bugs.
   size class regions interspersed with guard pages
 * Zero size allocations are a dedicated size class with the entire region
   remaining non-readable and non-writable
-* Extension for retrieving the size of allocations with fallback
+* Extension for retrieving the size of allocations with fallback [in-progress,
+  needs to be porting from the previous OpenBSD-based allocator]
   to a sentinel for pointers not managed by the allocator
     * Can also return accurate values for pointers *within* small allocations
     * The same applies to pointers within the first page of large allocations,