diff --git a/@xen-orchestra/immutable-backups/src/remote.integ.mts b/@xen-orchestra/immutable-backups/src/remote.integ.mts
index 883052a3e9..054357d3fc 100644
--- a/@xen-orchestra/immutable-backups/src/remote.integ.mts
+++ b/@xen-orchestra/immutable-backups/src/remote.integ.mts
@@ -139,7 +139,13 @@ describe('protectRemotes/watchRemote', async () => {
       await fs.writeFile(path.join(vmDir, `${BACKUP_DATE}.json`), '{}')
 
       // The whole directory (and its contents) must become immutable.
+      // `chattr -R` flags the directory before recursing into its children, so
+      // waiting on the directory alone races with the files inside it.
       await waitFor(() => Directory.isImmutable(vhdDir))
+      await waitFor(() => Directory.isImmutable(blocks))
+      await waitFor(() => File.isImmutable(bat))
+      await waitFor(() => File.isImmutable(header))
+      await waitFor(() => File.isImmutable(footer))
 
       assert.strictEqual(await Directory.isImmutable(vhdDir), true, 'vhd dir should be immutable')
       assert.strictEqual(await File.isImmutable(bat), true, 'bat should be immutable')