diff --git a/README.md b/README.md
index 0b8ab47..03306b3 100644
--- a/README.md
+++ b/README.md
@@ -8,3 +8,4 @@ Just run `make` here to build everything, including the book `frap.pdf` and the
 
 * Chapter 2: `BasicSyntax.v`
 * Chapter 3: `Interpreters.v`
+* Chapter 4: `TransitionSystems.v`