diff --git a/tests/qemu-iotests/186.out b/tests/qemu-iotests/186.out
index 01530040e5..27316bba46 100644
--- a/tests/qemu-iotests/186.out
+++ b/tests/qemu-iotests/186.out
@@ -57,7 +57,7 @@ qdev_id: [not inserted]
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device ide-hd,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      /machine/peripheral-anon/device[N]
     Cache mode:       writeback
 (qemu) quit
@@ -65,7 +65,7 @@ null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device ide-hd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Cache mode:       writeback
 (qemu) quit
@@ -73,7 +73,7 @@ null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device scsi-hd,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      /machine/peripheral-anon/device[N]
     Cache mode:       writeback
 (qemu) quit
@@ -81,7 +81,7 @@ null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device scsi-hd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Cache mode:       writeback
 (qemu) quit
@@ -89,7 +89,7 @@ null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device virtio-blk-pci,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      /machine/peripheral-anon/device[N]/virtio-backend
     Cache mode:       writeback
 (qemu) quit
@@ -97,7 +97,7 @@ null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device virtio-blk-pci,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      /machine/peripheral/qdev_id/virtio-backend
     Cache mode:       writeback
 (qemu) quit
@@ -105,7 +105,7 @@ null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device floppy,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      /machine/peripheral-anon/device[N]
     Removable device: not locked, tray closed
     Cache mode:       writeback
@@ -114,7 +114,7 @@ null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device floppy,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
@@ -123,7 +123,7 @@ null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device ide-cd,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      /machine/peripheral-anon/device[N]
     Removable device: not locked, tray closed
     Cache mode:       writeback
@@ -132,7 +132,7 @@ null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device ide-cd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
@@ -141,7 +141,7 @@ null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device scsi-cd,drive=null
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      /machine/peripheral-anon/device[N]
     Removable device: not locked, tray closed
     Cache mode:       writeback
@@ -150,7 +150,7 @@ null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
 Testing: -blockdev driver=null-co,read-zeroes=on,node-name=null -device scsi-cd,drive=null,id=qdev_id
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) info block
-null: json:{"read-zeroes": true, "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": true, "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
@@ -166,7 +166,7 @@ none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Cache mode:       writeback
 (qemu) quit
@@ -178,7 +178,7 @@ none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Cache mode:       writeback
 (qemu) quit
@@ -190,7 +190,7 @@ none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      /machine/peripheral/qdev_id/virtio-backend
     Cache mode:       writeback
 (qemu) quit
@@ -202,7 +202,7 @@ none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
@@ -215,7 +215,7 @@ none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
@@ -228,7 +228,7 @@ none0 (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Removable device: not locked, tray closed
     Cache mode:       writeback
 
-null: json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
+null (null): json:{"read-zeroes": "on", "driver": "null-co"} (null-co)
     Attached to:      qdev_id
     Removable device: not locked, tray closed
     Cache mode:       writeback
