diff --git a/block/vhdx.c b/block/vhdx.c
index 9918ee9..ab747f6 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1983,6 +1983,7 @@
     .bdrv_open              = vhdx_open,
     .bdrv_close             = vhdx_close,
     .bdrv_reopen_prepare    = vhdx_reopen_prepare,
+    .bdrv_child_perm        = bdrv_format_default_perms,
     .bdrv_co_readv          = vhdx_co_readv,
     .bdrv_co_writev         = vhdx_co_writev,
     .bdrv_create            = vhdx_create,