diff --git a/Readme.md b/Readme.md
index 318ac226461f..643611ce74f1 100644
--- a/Readme.md
+++ b/Readme.md
@@ -7,6 +7,7 @@
 ```bash
 $ git clone https://github.com/bjorn3/rustc_codegen_cranelift.git
 $ cd rustc_codegen_cranelift
+$ rustup override set nightly
 $ git submodule update --init
 $ cargo build
 ```