diff --git a/src/test/ui-fulldeps/pathless-extern-unstable.rs b/src/test/ui-fulldeps/pathless-extern-unstable.rs
index a5a31816c957..00b3ec5409ff 100644
--- a/src/test/ui-fulldeps/pathless-extern-unstable.rs
+++ b/src/test/ui-fulldeps/pathless-extern-unstable.rs
@@ -5,6 +5,6 @@
 // Test that `--extern rustc` fails with `rustc_private`.
 
 pub use rustc;
-//~^ use of unstable library feature 'rustc_private'
+//~^ ERROR use of unstable library feature 'rustc_private'
 
 fn main() {}