diff --git a/service/storage_devices.go b/service/storage_devices.go
index f12bdfd..527074f 100644
--- a/service/storage_devices.go
+++ b/service/storage_devices.go
@@ -155,16 +155,20 @@ func StorageUsage(disks []model.LSBLKModel) FilesystemStats {
 }
 
 // DiskInUse says whether a disk holds anything that must not be offered for
-// formatting: a filesystem or swap mounted anywhere below it, or a part of it
-// that belongs to a RAID array, a volume group or a ZFS pool, whether or not
-// that array, group or pool is assembled right now.
+// formatting: a filesystem or swap mounted anywhere below it, a part of it that
+// belongs to a RAID array, a volume group or a ZFS pool, whether or not that
+// array, group or pool is assembled right now, or an encrypted volume (LUKS,
+// BitLocker), open or not. A locked container mounts nothing and its format is
+// not one CasaOS reads, so formatting was the only thing offered for it.
 func DiskInUse(disk model.LSBLKModel) bool {
 	switch {
 	case disk.MountPoint != "",
 		strings.HasPrefix(disk.Type, "raid"),
 		disk.FsType == "linux_raid_member",
 		disk.FsType == "LVM2_member",
-		disk.FsType == "zfs_member":
+		disk.FsType == "zfs_member",
+		disk.FsType == "crypto_LUKS",
+		disk.FsType == "BitLocker":
 		return true
 	}
 	for _, child := range disk.Children {
diff --git a/service/storage_devices_test.go b/service/storage_devices_test.go
index 7cb196c..5b5057b 100644
--- a/service/storage_devices_test.go
+++ b/service/storage_devices_test.go
@@ -173,6 +173,12 @@ func TestADiskIsInUseWhenAnythingBelowItIs(t *testing.T) {
 		"a partition in a volume group": {Children: []model.LSBLKModel{{FsType: "LVM2_member"}}},
 		"a ZFS pool member":             {FsType: "zfs_member"},
 		"swap on a partition":           {Children: []model.LSBLKModel{{MountPoint: "[SWAP]"}}},
+		"a locked LUKS partition":       {Children: []model.LSBLKModel{{FsType: "crypto_LUKS"}}},
+		"a BitLocker partition":         {Children: []model.LSBLKModel{{FsType: "BitLocker"}}},
+		// LUKS, then dm-crypt, then LVM, then ext4 mounted from fstab (upstream #73's box)
+		"an opened LUKS stack": {Children: []model.LSBLKModel{{FsType: "crypto_LUKS", Children: []model.LSBLKModel{
+			{Type: "crypt", FsType: "LVM2_member", Children: []model.LSBLKModel{{Type: "lvm", FsType: "ext4", MountPoint: "/mnt/sata"}}},
+		}}}},
 	} {
 		if !DiskInUse(disk) {
 			t.Errorf("%s: offered for formatting", name)