Fixes #15765

Change-Id: Id0a89d90ef9d3fffa9af0affca8c10a26fe6b7bc
Reviewed-on: https://go-review.googlesource.com/23284
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>