Fixes #17838

Change-Id: Ifafb4542a0ed6f2e29c9a83e30842e2fc18d6546
Reviewed-on: https://go-review.googlesource.com/33015
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tom Bergan <tombergan@google.com>
Reviewed-by: Michael Munday <munday@ca.ibm.com>