diff --git a/LIMITS.md b/LIMITS.md
index 8278f18..f45e1a4 100644
--- a/LIMITS.md
+++ b/LIMITS.md
@@ -17,3 +17,5 @@ Known differences
 - Only support `res.text()` and `res.json()` at the moment, until there are good use-cases for blob.
 
 - There is currently no built-in caching, as server-side caching varies by use-cases.
+
+- Avoid using `Request` and `Response` constructors directly, as they are not spec-compliant yet (see open issues).