Fixes #14924

Change-Id: I098ef973e2cad76a121704492758c2971a9b55f3
Reviewed-on: https://go-review.googlesource.com/20920
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>