diff --git a/backends/modular-backend.cpp b/backends/modular-backend.cpp
index 5073ceae7eb..1fd3428c206 100644
--- a/backends/modular-backend.cpp
+++ b/backends/modular-backend.cpp
@@ -26,23 +26,19 @@
 #include "backends/mutex/mutex.h"
 #include "gui/EventRecorder.h"
 
-#include "audio/mixer.h"
 #include "common/timer.h"
 #include "graphics/pixelformat.h"
 
 ModularBackend::ModularBackend()
 	:
 	_mutexManager(0),
-	_graphicsManager(0),
-	_mixer(0) {
+	_graphicsManager(0) {
 
 }
 
 ModularBackend::~ModularBackend() {
 	delete _graphicsManager;
 	_graphicsManager = 0;
-	delete _mixer;
-	_mixer = 0;
 	// _timerManager needs to be deleted before _mutexManager to avoid a crash.
 	delete _timerManager;
 	_timerManager = 0;
@@ -271,11 +267,6 @@ void ModularBackend::deleteMutex(MutexRef mutex) {
 	_mutexManager->deleteMutex(mutex);
 }
 
-Audio::Mixer *ModularBackend::getMixer() {
-	assert(_mixer);
-	return (Audio::Mixer *)_mixer;
-}
-
 void ModularBackend::displayMessageOnOSD(const char *msg) {
 	_graphicsManager->displayMessageOnOSD(msg);
 }
diff --git a/backends/modular-backend.h b/backends/modular-backend.h
index ca4356de52d..e57dbf174f5 100644
--- a/backends/modular-backend.h
+++ b/backends/modular-backend.h
@@ -40,6 +40,7 @@ class MutexManager;
  *   OSystem::getMillis()
  *   OSystem::delayMillis()
  *   OSystem::getTimeAndDate()
+ *   OSystem::getMixer()
  *   OSystem::quit()
  *
  * And, it should also initialize all the managers variables
@@ -125,13 +126,6 @@ public:
 
 	//@}
 
-	/** @name Sound */
-	//@{
-
-	virtual Audio::Mixer *getMixer() override;
-
-	//@}
-
 	/** @name Miscellaneous */
 	//@{
 
@@ -146,7 +140,6 @@ protected:
 
 	MutexManager *_mutexManager;
 	GraphicsManager *_graphicsManager;
-	Audio::Mixer *_mixer;
 
 	//@}
 };
diff --git a/backends/platform/null/null.cpp b/backends/platform/null/null.cpp
index 2da3266e991..636ad5004bf 100644
--- a/backends/platform/null/null.cpp
+++ b/backends/platform/null/null.cpp
@@ -79,17 +79,21 @@ public:
 	virtual void delayMillis(uint msecs);
 	virtual void getTimeAndDate(TimeDate &t) const;
 
+	virtual Audio::Mixer *getMixer();
+
 	virtual void quit();
 
 	virtual void logMessage(LogMessageType::Type type, const char *message);
 
-#ifdef POSIX
 private:
+	Audio::MixerImpl *_mixer;
+
+#ifdef POSIX
 	timeval _startTime;
 #endif
 };
 
-OSystem_NULL::OSystem_NULL() {
+OSystem_NULL::OSystem_NULL() : _mixer(0) {
 	#if defined(__amigaos4__)
 		_fsFactory = new AmigaOSFilesystemFactory();
 	#elif defined(__MORPHOS__)	
@@ -106,6 +110,8 @@ OSystem_NULL::OSystem_NULL() {
 }
 
 OSystem_NULL::~OSystem_NULL() {
+	delete _mixer;
+	_mixer = 0;
 }
 
 #ifdef POSIX
@@ -133,7 +139,7 @@ void OSystem_NULL::initBackend() {
 	_graphicsManager = new NullGraphicsManager();
 	_mixer = new Audio::MixerImpl(22050);
 
-	((Audio::MixerImpl *)_mixer)->setReady(false);
+	_mixer->setReady(false);
 
 	// Note that the mixer is useless this way; it needs to be hooked
 	// into the system somehow to be functional. Of course, can't do
@@ -197,6 +203,11 @@ void OSystem_NULL::getTimeAndDate(TimeDate &td) const {
 	td.tm_wday = t.tm_wday;
 }
 
+Audio::Mixer *OSystem_NULL::getMixer() {
+	assert(_mixer);
+	return (Audio::Mixer *)_mixer;
+}
+
 void OSystem_NULL::quit() {
 	exit(0);
 }