Fixes #18289

Change-Id: I047e98cc36b861ef15292170aeaff8bc29243cab
Reviewed-on: https://go-review.googlesource.com/34281Reviewed-by: Russ Cox <rsc@golang.org>
(cherry picked from commit 265e5476)
Reviewed-on: https://go-review.googlesource.com/34282