diff --git a/library/std/tests/switch-stdout.rs b/library/std/tests/switch-stdout.rs
index 28ce6dfccd3..2605664d289 100644
--- a/library/std/tests/switch-stdout.rs
+++ b/library/std/tests/switch-stdout.rs
@@ -1,4 +1,4 @@
-#[cfg(any(target_family = "unix", target_family = "windows"))]
+#![cfg(any(target_family = "unix", target_family = "windows"))]
 
 use std::fs::File;
 use std::io::{Read, Write};