java.nio.charset.MalformedInputException when reading a stream

I use the following code to read data. It throws java.nio.charset.MalformedInputException. The file I can open normally, but it does include non-ascii chars. Anyway I can fix this problem?

  Source.fromInputStream(stream).getLines foreach { line =>
    // store items on the fly
    lineParser(line.trim) match {
      case None => // no-op
      case Some(pair) => // some-op
    }   
  }   
  stream.close()

The stream construction code is here:

def getStream(path: String) = {
  if (!fileExists(path)) {
    None
  } else {
    val fileURL = new URL(path)
    val urlConnection = fileURL.openConnection
    Some(urlConnection.getInputStream())
  }
}