diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 11bfc7a47cc48..4fdfb744f381c 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -201,6 +201,7 @@ struct Build {
     target: Vec<String>,
     cargo: Option<String>,
     rustc: Option<String>,
+    rustfmt: Option<String>, /* allow bootstrap.py to use rustfmt key */
     docs: Option<bool>,
     compiler_docs: Option<bool>,
     submodules: Option<bool>,