diff --git a/module/zfs/spa.c b/module/zfs/spa.c
index aa65fb6581..86447d1fdc 100644
--- a/module/zfs/spa.c
+++ b/module/zfs/spa.c
@@ -6772,10 +6772,12 @@ spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing,
 		return (spa_vdev_exit(spa, newrootvd, txg, error));
 
 	/*
-	 * Spares can't replace logs
+	 * log, dedup and special vdevs should not be replaced by spares.
 	 */
-	if (oldvd->vdev_top->vdev_islog && newvd->vdev_isspare)
+	if ((oldvd->vdev_top->vdev_alloc_bias != VDEV_BIAS_NONE ||
+	    oldvd->vdev_top->vdev_islog) && newvd->vdev_isspare) {
 		return (spa_vdev_exit(spa, newrootvd, txg, ENOTSUP));
+	}
 
 	/*
 	 * A dRAID spare can only replace a child of its parent dRAID vdev.
diff --git a/tests/zfs-tests/tests/functional/fault/auto_offline_001_pos.ksh b/tests/zfs-tests/tests/functional/fault/auto_offline_001_pos.ksh
index 86916bf906..d7189f2983 100755
--- a/tests/zfs-tests/tests/functional/fault/auto_offline_001_pos.ksh
+++ b/tests/zfs-tests/tests/functional/fault/auto_offline_001_pos.ksh
@@ -123,6 +123,11 @@ done
 #    the removed data device
 for conf in "${poolconfs[@]}"
 do
+	# special vdev can not be replaced by a hot spare
+	if [[ $conf = *"special mirror"* ]]; then
+		continue
+	fi
+
 	# 1. Create a pool with a spare
 	log_must zpool create -f $TESTPOOL $conf
 	block_device_wait ${DEV_DSKDIR}/${removedev}