Fixes #14195

Change-Id: I245b3ca3fd7d1a76aa95f2e058f8432ba5ce31ee
Reviewed-on: https://go-review.googlesource.com/19160
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>