diff --git a/README.md b/README.md
index 7cdbb4e..35b23d1 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 Install dependencies by
 
-    opam install menhir ocaml-vdom
+    opam install menhir ocaml-vdom ocamlformat
 
 and build Æff by running (requires OCaml >= 4.08.0)