diff --git a/libs/ardour/ardour/auditioner.h b/libs/ardour/ardour/auditioner.h
index 241f9bcef0..3340430e48 100644
--- a/libs/ardour/ardour/auditioner.h
+++ b/libs/ardour/ardour/auditioner.h
@@ -32,7 +32,6 @@ namespace ARDOUR {
 class Session;
 class AudioRegion;
 class AudioPlaylist;
-class MidiDiskstream;
 class MidiRegion;
 
 class LIBARDOUR_API Auditioner : public Track