Fixes #11752

Change-Id: If4196b4bbba4f1485608bfafa98fa54781177273
Reviewed-on: https://go-review.googlesource.com/12325Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>