Fixes #15962

Change-Id: I1949e0787f6c2b1e19b9f9d3af2f712606a6d4cf
Reviewed-on: https://go-review.googlesource.com/23786Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>