Fixes #17092

Change-Id: Ib14e4db13116ebbe4d72c414fb979d27a06d6174
Reviewed-on: https://go-review.googlesource.com/33011
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>