diff --git a/rfcs/syntax-singleton-types.md b/rfcs/syntax-singleton-types.md
index 26ea3028..9ecd3e46 100644
--- a/rfcs/syntax-singleton-types.md
+++ b/rfcs/syntax-singleton-types.md
@@ -2,6 +2,8 @@
 
 > Note: this RFC was adapted from an internal proposal that predates RFC process
 
+Status: Implemented
+
 ## Summary
 
 Introduce a new kind of type variable, called singleton types. They are just like normal types but has the capability to represent a constant runtime value as a type.