diff --git a/src/apps/mediaplayer/SoundOutput.h b/src/apps/mediaplayer/SoundOutput.h
index a17b528305..197c1c8726 100644
--- a/src/apps/mediaplayer/SoundOutput.h
+++ b/src/apps/mediaplayer/SoundOutput.h
@@ -22,6 +22,7 @@
 
 #include <MediaDefs.h>
 
+class BSoundPlayer;
 
 class SoundOutput
 {