diff --git a/src/test/ui/const-eval/promoted_errors.rs b/src/test/ui/const-eval/promoted_errors.rs
index c6d62e20576..dc30c7f9cce 100644
--- a/src/test/ui/const-eval/promoted_errors.rs
+++ b/src/test/ui/const-eval/promoted_errors.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 // compile-pass
-
+// compile-flags: -O
 fn main() {
     println!("{}", 0u32 - 1);
     //~^ WARN const_err