diff --git a/MediaBrowser.Model/Dlna/StreamBuilder.cs b/MediaBrowser.Model/Dlna/StreamBuilder.cs
index 84a6f6abe3..d2ca211505 100644
--- a/MediaBrowser.Model/Dlna/StreamBuilder.cs
+++ b/MediaBrowser.Model/Dlna/StreamBuilder.cs
@@ -1236,7 +1236,7 @@ namespace MediaBrowser.Model.Dlna
                 return (false, TranscodeReason.ContainerBitrateExceedsLimit);
             }
 
-            if (audioStream.IsExternal)
+            if (audioStream?.IsExternal == true)
             {
                 return (false, TranscodeReason.AudioIsExternal);
             }