diff --git a/Source/Engine/GraphicsDevice/DirectX/DX11/GPUBufferDX11.cpp b/Source/Engine/GraphicsDevice/DirectX/DX11/GPUBufferDX11.cpp
index e3ff0befe..5c98bf579 100644
--- a/Source/Engine/GraphicsDevice/DirectX/DX11/GPUBufferDX11.cpp
+++ b/Source/Engine/GraphicsDevice/DirectX/DX11/GPUBufferDX11.cpp
@@ -19,7 +19,8 @@ GPUBufferView* GPUBufferDX11::View() const
 
 void* GPUBufferDX11::Map(GPUResourceMapMode mode)
 {
-    if (!IsInMainThread())
+    const bool isMainThread = IsInMainThread();
+    if (!isMainThread)
         _device->Locker.Lock();
     ASSERT(!_mapped);
 
@@ -31,7 +32,7 @@ void* GPUBufferDX11::Map(GPUResourceMapMode mode)
     {
     case GPUResourceMapMode::Read:
         mapType = D3D11_MAP_READ;
-        if (_desc.Usage == GPUResourceUsage::StagingReadback)
+        if (_desc.Usage == GPUResourceUsage::StagingReadback && isMainThread)
             mapFlags = D3D11_MAP_FLAG_DO_NOT_WAIT;
         break;
     case GPUResourceMapMode::Write:
diff --git a/Source/Engine/ShadowsOfMordor/Builder.BuildCache.cpp b/Source/Engine/ShadowsOfMordor/Builder.BuildCache.cpp
index fb3ed6b2c..e2d19980c 100644
--- a/Source/Engine/ShadowsOfMordor/Builder.BuildCache.cpp
+++ b/Source/Engine/ShadowsOfMordor/Builder.BuildCache.cpp
@@ -103,7 +103,7 @@ void ShadowsOfMordor::Builder::SceneBuildCache::UpdateLightmaps()
         // Download buffer data
         if (lightmapEntry.LightmapData->DownloadData(ImportLightmapTextureData))
         {
-            LOG(Warning, "Cannot download LightmapData.");
+            LOG(Error, "Cannot download LightmapData.");
             return;
         }