Fixes #18402

Change-Id: I5af800857fb2e365ce4224eece9171277106ec7d
Reviewed-on: https://go-review.googlesource.com/35562
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>