diff --git a/scst/src/dev_handlers/scst_vdisk.c b/scst/src/dev_handlers/scst_vdisk.c
index 56f101770..66ef444e8 100644
--- a/scst/src/dev_handlers/scst_vdisk.c
+++ b/scst/src/dev_handlers/scst_vdisk.c
@@ -789,7 +789,7 @@ static struct scst_dev_type vdisk_blk_devtype = {
 static struct scst_dev_type vdisk_null_devtype = {
 	.name =			"vdisk_nullio",
 	.type =			TYPE_DISK,
-	.threads_num =		0,
+	.threads_num =		1,
 	.parse_atomic =		1,
 	.dev_done_atomic =	1,
 #ifdef CONFIG_SCST_PROC