diff --git a/src/test/ui/borrowck/borrowck-reinit.stderr b/src/test/ui/borrowck/borrowck-reinit.stderr
index 9f08bd19822..f36ed050515 100644
--- a/src/test/ui/borrowck/borrowck-reinit.stderr
+++ b/src/test/ui/borrowck/borrowck-reinit.stderr
@@ -15,6 +15,8 @@ error[E0382]: use of moved value: `x` (Mir)
    |          - value moved here
 18 |     let _ = (1,x); //~ ERROR use of moved value: `x` (Ast)
    |                ^ value used here after move
+   |
+   = note: move occurs because `x` has type `std::boxed::Box<i32>`, which does not implement the `Copy` trait
 
 error: aborting due to 2 previous errors