if (fileSystem.exists(dirty)) {
          val clean = entry.cleanFiles[i]
          fileSystem.atomicMove(dirty, clean)
          val oldLength = entry.lengths[i]
          // TODO check null behaviour
          val newLength = fileSystem.metadata(clean).size ?: 0
          entry.lengths[i] = newLength
          size = size - oldLength + newLength
        }
      } else {
        fileSystem.deleteIfExists(dirty)