Fix a regression introduced in r344569

Import a fix from illumos (thanks Toomas Soomas for pointing at it)

See https://www.illumos.org/issues/10205 for more details
Illumos commit: https://github.com/illumos/illumos-gate/commit/247b7da039fd88350c50e3d7fef15bdab6bef215

Submitted by: jack@gandi.net
Reported by: cy
Reviewed by: tsoome, cy, bapt
Obtained from: Illumos