Fixes #14278

Change-Id: I6a0c1370d595f0573ff0eb933450b1eea41f4bb3
Reviewed-on: https://go-review.googlesource.com/19452
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>