diff --git a/c89/README.md b/c89/README.md
index 7190bdf..8749d23 100644
--- a/c89/README.md
+++ b/c89/README.md
@@ -3,6 +3,8 @@
 This directory is a clean native C89 implementation of the language behavior
 present in the original TypeScript interpreter.
 
+Original project: https://github.com/lainq/peppermint
+
 Implemented subset:
 
 - `let name := expression` bindings