diff --git a/README.md b/README.md
index 7a685c6..1c1bca5 100644
--- a/README.md
+++ b/README.md
@@ -83,6 +83,9 @@ code name
 # 0x14 formerly had the name "sha3", now deprecated
 ```
 
+## Compatibility note
+
+Implementations should make sure keep the string code `sha3` as an alias for `sha3-512` so that `encode('sha3', digest) == encode('sha3-512', digest)`.
 
 ### other tables