diff --git a/bundles/zfs/files/backup-pre-hook b/bundles/zfs/files/backup-pre-hook
index ba2ce9b..ee1386b 100644
--- a/bundles/zfs/files/backup-pre-hook
+++ b/bundles/zfs/files/backup-pre-hook
@@ -10,7 +10,7 @@ mountpoint="/mnt/backup-snapshot${node.metadata['zfs']['datasets'][dataset]['mou
 
 if findmnt "$mountpoint" >/dev/null
 then
-    umount "$mountpoint" || errors=1
+    umount -R "$mountpoint" || errors=1
 fi
 
 if zfs get type "${dataset}@snapshot-backup" >/dev/null 2>&1