diff --git a/Source/Engine/Audio/AudioBackend.h b/Source/Engine/Audio/AudioBackend.h
index 61d2c223a..ccfea09c3 100644
--- a/Source/Engine/Audio/AudioBackend.h
+++ b/Source/Engine/Audio/AudioBackend.h
@@ -58,8 +58,8 @@ private:
     virtual void Source_DequeueProcessedBuffers(AudioSource* source) = 0;
 
     // Buffer
-    virtual void Buffer_Create(uint32& bufferId) = 0;
-    virtual void Buffer_Delete(uint32& bufferId) = 0;
+    virtual uint32 Buffer_Create() = 0;
+    virtual void Buffer_Delete(uint32 bufferId) = 0;
     virtual void Buffer_Write(uint32 bufferId, byte* samples, const AudioDataInfo& info) = 0;
 
     // Base
@@ -224,15 +224,14 @@ public:
     {
     public:
 
-        FORCE_INLINE static void Create(uint32& bufferId)
+        FORCE_INLINE static uint32 Create()
         {
-            Instance->Buffer_Create(bufferId);
+            return Instance->Buffer_Create();
         }
 
-        FORCE_INLINE static void Delete(uint32& bufferId)
+        FORCE_INLINE static void Delete(uint32 bufferId)
         {
-            if (Instance)
-                Instance->Buffer_Delete(bufferId);
+            Instance->Buffer_Delete(bufferId);
         }
 
         FORCE_INLINE static void Write(uint32 bufferId, byte* samples, const AudioDataInfo& info)
diff --git a/Source/Engine/Audio/AudioClip.cpp b/Source/Engine/Audio/AudioClip.cpp
index d91eb358c..8750bed03 100644
--- a/Source/Engine/Audio/AudioClip.cpp
+++ b/Source/Engine/Audio/AudioClip.cpp
@@ -19,7 +19,7 @@ REGISTER_BINARY_ASSET_WITH_UPGRADER(AudioClip, "FlaxEngine.AudioClip", AudioClip
 bool AudioClip::StreamingTask::Run()
 {
     AssetReference<AudioClip> ref = _asset.Get();
-    if (ref == nullptr)
+    if (ref == nullptr || AudioBackend::Instance == nullptr)
         return true;
     ScopeLock lock(ref->Locker);
     const auto& queue = ref->StreamingQueue;
@@ -34,13 +34,13 @@ bool AudioClip::StreamingTask::Run()
         uint32& bufferId = clip->Buffers[idx];
         if (bufferId == AUDIO_BUFFER_ID_INVALID)
         {
-            AudioBackend::Buffer::Create(bufferId);
+            bufferId = AudioBackend::Buffer::Create();
         }
         else
         {
             // Release unused data
             AudioBackend::Buffer::Delete(bufferId);
-            bufferId = 0;
+            bufferId = AUDIO_BUFFER_ID_INVALID;
         }
     }
 
@@ -370,9 +370,7 @@ Asset::LoadResult AudioClip::load()
         return LoadResult::CannotLoadData;
 
     // Create single buffer
-    uint32 bufferId;
-    AudioBackend::Buffer::Create(bufferId);
-    Buffers[0] = bufferId;
+    Buffers[0] = AudioBackend::Buffer::Create();
 
     // Write data to audio buffer
     if (WriteBuffer(0))
@@ -398,14 +396,12 @@ void AudioClip::unload(bool isReloading)
 
     StopStreaming();
     StreamingQueue.Clear();
-    if (hasAnyBuffer)
+    if (hasAnyBuffer && AudioBackend::Instance)
     {
         for (AUDIO_BUFFER_ID_TYPE bufferId : Buffers)
         {
             if (bufferId != AUDIO_BUFFER_ID_INVALID)
-            {
                 AudioBackend::Buffer::Delete(bufferId);
-            }
         }
     }
     Buffers.Clear();
diff --git a/Source/Engine/Audio/None/AudioBackendNone.cpp b/Source/Engine/Audio/None/AudioBackendNone.cpp
index 42a31b775..a56315bbe 100644
--- a/Source/Engine/Audio/None/AudioBackendNone.cpp
+++ b/Source/Engine/Audio/None/AudioBackendNone.cpp
@@ -114,12 +114,12 @@ void AudioBackendNone::Source_DequeueProcessedBuffers(AudioSource* source)
 {
 }
 
-void AudioBackendNone::Buffer_Create(uint32& bufferId)
+uint32 AudioBackendNone::Buffer_Create()
 {
-    bufferId = 1;
+    return 1;
 }
 
-void AudioBackendNone::Buffer_Delete(uint32& bufferId)
+void AudioBackendNone::Buffer_Delete(uint32 bufferId)
 {
 }
 
diff --git a/Source/Engine/Audio/None/AudioBackendNone.h b/Source/Engine/Audio/None/AudioBackendNone.h
index 1e90b42ac..e3f5134a6 100644
--- a/Source/Engine/Audio/None/AudioBackendNone.h
+++ b/Source/Engine/Audio/None/AudioBackendNone.h
@@ -40,8 +40,8 @@ public:
     void Source_GetQueuedBuffersCount(AudioSource* source, int32& queuedBuffersCount) override;
     void Source_QueueBuffer(AudioSource* source, uint32 bufferId) override;
     void Source_DequeueProcessedBuffers(AudioSource* source) override;
-    void Buffer_Create(uint32& bufferId) override;
-    void Buffer_Delete(uint32& bufferId) override;
+    uint32 Buffer_Create() override;
+    void Buffer_Delete(uint32 bufferId) override;
     void Buffer_Write(uint32 bufferId, byte* samples, const AudioDataInfo& info) override;
     const Char* Base_Name() override;
     FeatureFlags Base_Features() override;
diff --git a/Source/Engine/Audio/OpenAL/AudioBackendOAL.cpp b/Source/Engine/Audio/OpenAL/AudioBackendOAL.cpp
index cc5036e25..84642ac1f 100644
--- a/Source/Engine/Audio/OpenAL/AudioBackendOAL.cpp
+++ b/Source/Engine/Audio/OpenAL/AudioBackendOAL.cpp
@@ -589,13 +589,15 @@ void AudioBackendOAL::Source_DequeueProcessedBuffers(AudioSource* source)
     }
 }
 
-void AudioBackendOAL::Buffer_Create(uint32& bufferId)
+uint32 AudioBackendOAL::Buffer_Create()
 {
+    uint32 bufferId;
     alGenBuffers(1, &bufferId);
     ALC_CHECK_ERROR(alGenBuffers);
+    return bufferId;
 }
 
-void AudioBackendOAL::Buffer_Delete(uint32& bufferId)
+void AudioBackendOAL::Buffer_Delete(uint32 bufferId)
 {
     alDeleteBuffers(1, &bufferId);
     ALC_CHECK_ERROR(alDeleteBuffers);
diff --git a/Source/Engine/Audio/OpenAL/AudioBackendOAL.h b/Source/Engine/Audio/OpenAL/AudioBackendOAL.h
index 5590de518..daf981e8c 100644
--- a/Source/Engine/Audio/OpenAL/AudioBackendOAL.h
+++ b/Source/Engine/Audio/OpenAL/AudioBackendOAL.h
@@ -40,8 +40,8 @@ public:
     void Source_GetQueuedBuffersCount(AudioSource* source, int32& queuedBuffersCount) override;
     void Source_QueueBuffer(AudioSource* source, uint32 bufferId) override;
     void Source_DequeueProcessedBuffers(AudioSource* source) override;
-    void Buffer_Create(uint32& bufferId) override;
-    void Buffer_Delete(uint32& bufferId) override;
+    uint32 Buffer_Create() override;
+    void Buffer_Delete(uint32 bufferId) override;
     void Buffer_Write(uint32 bufferId, byte* samples, const AudioDataInfo& info) override;
     const Char* Base_Name() override;
     FeatureFlags Base_Features() override;
diff --git a/Source/Engine/Audio/XAudio2/AudioBackendXAudio2.cpp b/Source/Engine/Audio/XAudio2/AudioBackendXAudio2.cpp
index bbef7d421..698a6025a 100644
--- a/Source/Engine/Audio/XAudio2/AudioBackendXAudio2.cpp
+++ b/Source/Engine/Audio/XAudio2/AudioBackendXAudio2.cpp
@@ -9,6 +9,7 @@
 #include "Engine/Audio/Audio.h"
 #include "Engine/Audio/AudioSource.h"
 #include "Engine/Audio/AudioListener.h"
+#include "Engine/Threading/Threading.h"
 
 #if PLATFORM_WINDOWS
 // Tweak Win ver
@@ -206,6 +207,7 @@ namespace XAudio2
     UINT32 Channels;
     bool ForceDirty = true;
     Listener Listeners[AUDIO_MAX_LISTENERS];
+    CriticalSection Locker;
     Array<Source> Sources(32); // TODO: use ChunkedArray for better performance
     Array<Buffer*> Buffers(64); // TODO: use ChunkedArray for better performance or use buffers pool?
     EngineCallback Callback;
@@ -306,7 +308,6 @@ void AudioBackendXAudio2::Listener_OnAdd(AudioListener* listener)
 
 void AudioBackendXAudio2::Listener_OnRemove(AudioListener* listener)
 {
-    // Free listener
     XAudio2::Listener* aListener = XAudio2::GetListener(listener);
     if (aListener)
     {
@@ -346,6 +347,7 @@ void AudioBackendXAudio2::Source_OnAdd(AudioSource* source)
     if (source->Clip == nullptr || !source->Clip->IsLoaded())
         return;
     auto clip = source->Clip.Get();
+    ScopeLock lock(XAudio2::Locker);
 
     // Get first free source
     XAudio2::Source* aSource = nullptr;
@@ -419,6 +421,7 @@ void AudioBackendXAudio2::Source_OnAdd(AudioSource* source)
 
 void AudioBackendXAudio2::Source_OnRemove(AudioSource* source)
 {
+    ScopeLock lock(XAudio2::Locker);
     source->Cleanup();
 }
 
@@ -485,8 +488,10 @@ void AudioBackendXAudio2::Source_IsLoopingChanged(AudioSource* source)
 
     // Looping is defined during buffer submission so reset source buffer (this is called only for non-streamable sources that ue single buffer)
 
+    XAudio2::Locker.Lock();
     const uint32 bufferId = source->Clip->Buffers[0];
     XAudio2::Buffer* aBuffer = XAudio2::Buffers[bufferId - 1];
+    XAudio2::Locker.Unlock();
 
     const bool isPlaying = source->IsActuallyPlayingSth();
     if (isPlaying)
@@ -536,6 +541,7 @@ void AudioBackendXAudio2::Source_SpatialSetupChanged(AudioSource* source)
 
 void AudioBackendXAudio2::Source_ClipLoaded(AudioSource* source)
 {
+    ScopeLock lock(XAudio2::Locker);
     auto aSource = XAudio2::GetSource(source);
     if (!aSource)
     {
@@ -546,6 +552,7 @@ void AudioBackendXAudio2::Source_ClipLoaded(AudioSource* source)
 
 void AudioBackendXAudio2::Source_Cleanup(AudioSource* source)
 {
+    ScopeLock lock(XAudio2::Locker);
     auto aSource = XAudio2::GetSource(source);
     if (!aSource)
         return;
@@ -632,8 +639,10 @@ void AudioBackendXAudio2::Source_SetNonStreamingBuffer(AudioSource* source)
     if (!aSource)
         return;
 
+    XAudio2::Locker.Lock();
     const uint32 bufferId = source->Clip->Buffers[0];
     XAudio2::Buffer* aBuffer = XAudio2::Buffers[bufferId - 1];
+    XAudio2::Locker.Unlock();
 
     XAUDIO2_BUFFER buffer = { 0 };
     buffer.pContext = aBuffer;
@@ -695,8 +704,11 @@ void AudioBackendXAudio2::Source_DequeueProcessedBuffers(AudioSource* source)
     }
 }
 
-void AudioBackendXAudio2::Buffer_Create(uint32& bufferId)
+uint32 AudioBackendXAudio2::Buffer_Create()
 {
+    uint32 bufferId;
+    ScopeLock lock(XAudio2::Locker);
+
     // Get first free buffer slot
     XAudio2::Buffer* aBuffer = nullptr;
     for (int32 i = 0; i < XAudio2::Buffers.Count(); i++)
@@ -718,10 +730,12 @@ void AudioBackendXAudio2::Buffer_Create(uint32& bufferId)
     }
 
     aBuffer->Data.Resize(0);
+    return bufferId;
 }
 
-void AudioBackendXAudio2::Buffer_Delete(uint32& bufferId)
+void AudioBackendXAudio2::Buffer_Delete(uint32 bufferId)
 {
+    ScopeLock lock(XAudio2::Locker);
     XAudio2::Buffer*& aBuffer = XAudio2::Buffers[bufferId - 1];
     aBuffer->Data.Resize(0);
     Delete(aBuffer);
@@ -730,7 +744,9 @@ void AudioBackendXAudio2::Buffer_Delete(uint32& bufferId)
 
 void AudioBackendXAudio2::Buffer_Write(uint32 bufferId, byte* samples, const AudioDataInfo& info)
 {
+    XAudio2::Locker.Lock();
     XAudio2::Buffer* aBuffer = XAudio2::Buffers[bufferId - 1];
+    XAudio2::Locker.Unlock();
 
     const uint32 bytesPerSample = info.BitDepth / 8;
     const int32 samplesLength = info.NumSamples * bytesPerSample;
diff --git a/Source/Engine/Audio/XAudio2/AudioBackendXAudio2.h b/Source/Engine/Audio/XAudio2/AudioBackendXAudio2.h
index 1257cb2df..52df27eff 100644
--- a/Source/Engine/Audio/XAudio2/AudioBackendXAudio2.h
+++ b/Source/Engine/Audio/XAudio2/AudioBackendXAudio2.h
@@ -40,8 +40,8 @@ public:
     void Source_GetQueuedBuffersCount(AudioSource* source, int32& queuedBuffersCount) override;
     void Source_QueueBuffer(AudioSource* source, uint32 bufferId) override;
     void Source_DequeueProcessedBuffers(AudioSource* source) override;
-    void Buffer_Create(uint32& bufferId) override;
-    void Buffer_Delete(uint32& bufferId) override;
+    uint32 Buffer_Create() override;
+    void Buffer_Delete(uint32 bufferId) override;
     void Buffer_Write(uint32 bufferId, byte* samples, const AudioDataInfo& info) override;
     const Char* Base_Name() override;
     FeatureFlags Base_Features() override;