5 files changed, 7 insertions, 3 deletions
diff --git a/sound/audiocd.cpp b/sound/audiocd.cpp
index aafa279ed8..e8a74d062c 100644
--- a/sound/audiocd.cpp
+++ b/sound/audiocd.cpp
@@ -28,6 +28,7 @@
 #include "base/engine.h"
 #include "common/file.h"
 #include "common/util.h"
+#include "common/system.h"
 
 struct TrackFormat {
 	/** Decodername */
diff --git a/sound/mixer.cpp b/sound/mixer.cpp
index a981e32cda..050f37f8ec 100644
--- a/sound/mixer.cpp
+++ b/sound/mixer.cpp
@@ -21,8 +21,10 @@
  */
 
 #include "stdafx.h"
+
 #include "common/file.h"
 #include "common/util.h"
+#include "common/system.h"
 
 #include "sound/mixer.h"
 #include "sound/rate.h"
diff --git a/sound/mixer.h b/sound/mixer.h
index ecfbc19b12..44f552fd9c 100644
--- a/sound/mixer.h
+++ b/sound/mixer.h
@@ -25,12 +25,13 @@
 
 #include "stdafx.h"
 #include "common/scummsys.h"
-#include "common/system.h"
+#include "common/mutex.h"
 
 
 class AudioStream;
 class Channel;
 class File;
+class OSystem;
 
 class PlayingSoundHandle {
 	friend class Channel;
@@ -88,7 +89,7 @@ private:
 	};
 
 	OSystem *_syst;
-	OSystem::MutexRef _mutex;
+	Common::MutexRef _mutex;
 
 	Channel *_premixChannel;
 
diff --git a/sound/mpu401.h b/sound/mpu401.h
index 9c5529934f..7b722df7c9 100644
--- a/sound/mpu401.h
+++ b/sound/mpu401.h
@@ -23,7 +23,6 @@
 #define SOUND_MPU401_H
 
 #include "stdafx.h"
-#include "common/system.h"
 #include "mididrv.h"
 
 ////////////////////////////////////////
diff --git a/sound/softsynth/mt32.cpp b/sound/softsynth/mt32.cpp
index 358cfacc84..44221b91b1 100644
--- a/sound/softsynth/mt32.cpp
+++ b/sound/softsynth/mt32.cpp
@@ -31,6 +31,7 @@
 #include "common/util.h"
 #include "common/file.h"
 #include "common/config-manager.h"
+#include "common/system.h"
 
 #include "graphics/fontman.h"
 #include "graphics/surface.h"