Fixes #14505.

Change-Id: I46196b26c9339609e6e3ef9159de38c5b50c2a1b
Reviewed-on: https://go-review.googlesource.com/23922
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Andrew Gerrand <adg@golang.org>