Fixes #17683

Change-Id: I46f45c63796b58e8a8f14e37592231cbe7cd6934
Reviewed-on: https://go-review.googlesource.com/32438Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>