diff --git a/README.md b/README.md
index 9fbde28..4084946 100644
--- a/README.md
+++ b/README.md
@@ -30,6 +30,7 @@ Custom firmware USB device: 1CCF:2333
 
 ```
 $ git clone ...
+$ git submodule update --init
 $ zig build -Drelease-fast=true
 $ ls zig-out/lib/chuniio_tasoller.dll
 ```