diff --git a/block/null.c b/block/null.c
index 15e1d56746..cc9b1d4ea7 100644
--- a/block/null.c
+++ b/block/null.c
@@ -262,6 +262,11 @@ static void null_refresh_filename(BlockDriverState *bs)
              bs->drv->format_name);
 }
 
+static int64_t null_allocated_file_size(BlockDriverState *bs)
+{
+    return 0;
+}
+
 static const char *const null_strong_runtime_opts[] = {
     BLOCK_OPT_SIZE,
     NULL_OPT_ZEROES,
@@ -277,6 +282,7 @@ static BlockDriver bdrv_null_co = {
     .bdrv_file_open         = null_file_open,
     .bdrv_parse_filename    = null_co_parse_filename,
     .bdrv_getlength         = null_getlength,
+    .bdrv_get_allocated_file_size = null_allocated_file_size,
 
     .bdrv_co_preadv         = null_co_preadv,
     .bdrv_co_pwritev        = null_co_pwritev,
@@ -297,6 +303,7 @@ static BlockDriver bdrv_null_aio = {
     .bdrv_file_open         = null_file_open,
     .bdrv_parse_filename    = null_aio_parse_filename,
     .bdrv_getlength         = null_getlength,
+    .bdrv_get_allocated_file_size = null_allocated_file_size,
 
     .bdrv_aio_preadv        = null_aio_preadv,
     .bdrv_aio_pwritev       = null_aio_pwritev,
diff --git a/tests/qemu-iotests/153.out b/tests/qemu-iotests/153.out
index 8a79e1ee87..fcaa71aeee 100644
--- a/tests/qemu-iotests/153.out
+++ b/tests/qemu-iotests/153.out
@@ -464,7 +464,7 @@ No conflict:
 image: null-co://
 file format: null-co
 virtual size: 1 GiB (1073741824 bytes)
-disk size: unavailable
+disk size: 0 B
 
 Conflict:
 qemu-img: --force-share/-U conflicts with image options
diff --git a/tests/qemu-iotests/184 b/tests/qemu-iotests/184
index 33dd8d2a4f..eebb53faed 100755
--- a/tests/qemu-iotests/184
+++ b/tests/qemu-iotests/184
@@ -45,8 +45,7 @@ do_run_qemu()
 run_qemu()
 {
     do_run_qemu "$@" 2>&1 | _filter_testdir | _filter_qemu | _filter_qmp\
-                          | _filter_qemu_io | _filter_generated_node_ids \
-                          | _filter_actual_image_size
+                          | _filter_qemu_io | _filter_generated_node_ids
 }
 
 test_throttle=$($QEMU_IMG --help|grep throttle)
diff --git a/tests/qemu-iotests/184.out b/tests/qemu-iotests/184.out
index 3deb3cfb94..dec4017ad5 100644
--- a/tests/qemu-iotests/184.out
+++ b/tests/qemu-iotests/184.out
@@ -29,7 +29,8 @@ Testing:
             "image": {
                 "virtual-size": 1073741824,
                 "filename": "json:{\"throttle-group\": \"group0\", \"driver\": \"throttle\", \"file\": {\"driver\": \"null-co\"}}",
-                "format": "throttle"
+                "format": "throttle",
+                "actual-size": 0
             },
             "iops_wr": 0,
             "ro": false,
@@ -56,7 +57,8 @@ Testing:
             "image": {
                 "virtual-size": 1073741824,
                 "filename": "null-co://",
-                "format": "null-co"
+                "format": "null-co",
+                "actual-size": 0
             },
             "iops_wr": 0,
             "ro": false,