diff --git a/README.md b/README.md
index 2df02a9..f6f1049 100644
--- a/README.md
+++ b/README.md
@@ -10,4 +10,9 @@ Typed/Racket.
 
 * The API should hopefully remain stable, even if struct type properties
   become supported (this library will then become a wrapper) or forbidden in
-  Typed/Racket (this library will then use typed/racket/unsafe tricks).
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+  Typed/Racket (this library will then use typed/racket/unsafe tricks).
+
+Currently, the following properties are supported:
+
+* prop:custom-write
+* prop:equal+hash
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