Fixes #18122

Change-Id: Ib4067422c0c447ddb2c3068dc6217393abc4eed0
Reviewed-on: https://go-review.googlesource.com/80175
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>