Fixes #21518

Change-Id: Idd67e3f0410d0ce991b34dcc0c8f15e0d5c529c9
Reviewed-on: https://go-review.googlesource.com/56891
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Petrica Voicu <pvoicu@paypal.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>