diff --git a/src/test/ui/consts/const_discriminant.rs b/src/test/ui/consts/const_discriminant.rs
index a9c0217ae2421..f623c5101f4cd 100644
--- a/src/test/ui/consts/const_discriminant.rs
+++ b/src/test/ui/consts/const_discriminant.rs
@@ -27,6 +27,7 @@ const TEST_V: Discriminant<SingleVariant> = discriminant(&SingleVariant::V);
 
 pub const TEST_VOID: () = {
     // This is UB, but CTFE does not check validity so it does not detect this.
+    // This is a regression test for https://github.com/rust-lang/rust/issues/89765.
     unsafe { std::mem::discriminant(&*(&() as *const () as *const Void)); };
 };