diff --git a/y.rs b/y.rs
index 18528d54297..e412288b938 100755
--- a/y.rs
+++ b/y.rs
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-#![allow()] /*This line is ignored by bash
+#![deny(unsafe_code)] /*This line is ignored by bash
 # This block is ignored by rustc
 set -e
 echo "[BUILD] y.rs" 1>&2