Fortify : XSLT Injection attacks fix

Question

Fortify scan results show me a xslt injection attack warning on the below code

  public Saxon.Api.XsltTransformer transformer = null;

  using (System.IO.StreamReader reader = new StreamReader("C://Document.xsl", System.Text.Encoding.UTF8)) **//warning source**
  using (System.IO.Stream xslStream = reader.BaseStream)
  {
     transformer = new Saxon.Api.Processor().NewXsltCompiler().Compile(xslStream).Load(); **//warning line**
  }

How can I resolve this situation ?

Note : it doesn't give any error it says this line of code is suspicious