diff --git a/block/src/vhdx_sync.rs b/block/src/vhdx_sync.rs
index a99f4f6f9..7a863a864 100644
--- a/block/src/vhdx_sync.rs
+++ b/block/src/vhdx_sync.rs
@@ -14,8 +14,9 @@ use crate::async_io::{
 };
 use crate::error::{BlockError, BlockErrorKind, BlockResult, ErrorOp};
 use crate::vhdx::Vhdx;
-use crate::{AsyncAdaptor, BlockBackend, Error};
+use crate::{AsyncAdaptor, BlockBackend, Error, disk_file};
 
+#[derive(Debug)]
 pub struct VhdxDiskSync {
     // FIXME: The Mutex serializes all VHDX I/O operations across queues, which
     // is necessary for correctness but eliminates any parallelism benefit from
@@ -38,6 +39,12 @@ impl VhdxDiskSync {
     }
 }
 
+impl disk_file::DiskSize for VhdxDiskSync {
+    fn logical_size(&self) -> BlockResult<u64> {
+        Ok(self.vhdx_file.lock().unwrap().virtual_disk_size())
+    }
+}
+
 impl DiskFile for VhdxDiskSync {
     fn logical_size(&mut self) -> DiskFileResult<u64> {
         Ok(self.vhdx_file.lock().unwrap().virtual_disk_size())