diff --git a/src/d3d11/d3d11_context_def.cpp b/src/d3d11/d3d11_context_def.cpp
index 924a2d175..786dcf2e9 100644
--- a/src/d3d11/d3d11_context_def.cpp
+++ b/src/d3d11/d3d11_context_def.cpp
@@ -70,6 +70,12 @@ namespace dxvk {
     D3D11_RESOURCE_DIMENSION resourceDim = D3D11_RESOURCE_DIMENSION_UNKNOWN;
     pResource->GetType(&resourceDim);
     
+    if (pMappedResource != nullptr) {
+      pMappedResource->pData      = nullptr;
+      pMappedResource->RowPitch   = 0;
+      pMappedResource->DepthPitch = 0;
+    }
+    
     if (MapType != D3D11_MAP_WRITE_DISCARD
      && MapType != D3D11_MAP_WRITE_NO_OVERWRITE)
       return E_INVALIDARG;
@@ -115,9 +121,6 @@ namespace dxvk {
       return E_INVALIDARG;
     }
     
-    if (pMappedResource == nullptr)
-      return S_FALSE;
-    
     auto entry = FindMapEntry(pResource, 0);
     
     if (MapType == D3D11_MAP_WRITE_DISCARD) {
diff --git a/src/d3d11/d3d11_context_imm.cpp b/src/d3d11/d3d11_context_imm.cpp
index 492da900c..ded6eea66 100644
--- a/src/d3d11/d3d11_context_imm.cpp
+++ b/src/d3d11/d3d11_context_imm.cpp
@@ -44,7 +44,8 @@ namespace dxvk {
   void STDMETHODCALLTYPE D3D11ImmediateContext::Flush() {
     m_parent->FlushInitContext();
     
-    if (m_csChunk->commandCount() != 0) {
+    if (m_csIsBusy || m_csChunk->commandCount() != 0) {
+      m_csIsBusy  = false;
       m_drawCount = 0;
       
       // Add commands to flush the threaded
@@ -74,6 +75,8 @@ namespace dxvk {
       RestoreState();
     else
       ClearState();
+    
+    m_csIsBusy = true;
   }
   
   
@@ -95,7 +98,13 @@ namespace dxvk {
       Logger::warn("D3D11ImmediateContext::Map() application tried to map a nullptr resource");
       return DXGI_ERROR_INVALID_CALL;
     }
-
+    
+    if (pMappedResource != nullptr) {
+      pMappedResource->pData      = nullptr;
+      pMappedResource->RowPitch   = 0;
+      pMappedResource->DepthPitch = 0;
+    }
+    
     D3D11_RESOURCE_DIMENSION resourceDim = D3D11_RESOURCE_DIMENSION_UNKNOWN;
     pResource->GetType(&resourceDim);
     
@@ -199,9 +208,6 @@ namespace dxvk {
       return E_INVALIDARG;
     }
     
-    if (pMappedResource == nullptr)
-      return S_FALSE;
-    
     // Parameter validation was successful
     VkImageSubresource subresource =
       pResource->GetSubresourceFromIndex(
@@ -218,8 +224,7 @@ namespace dxvk {
       
       // Query the subresource's memory layout and hope that
       // the application respects the returned pitch values.
-      VkSubresourceLayout layout = mappedImage->querySubresourceLayout(subresource);
-      
+      VkSubresourceLayout layout  = mappedImage->querySubresourceLayout(subresource);
       pMappedResource->pData      = mappedImage->mapPtr(layout.offset);
       pMappedResource->RowPitch   = imageType >= VK_IMAGE_TYPE_2D ? layout.rowPitch   : layout.size;
       pMappedResource->DepthPitch = imageType >= VK_IMAGE_TYPE_3D ? layout.depthPitch : layout.size;
@@ -239,14 +244,12 @@ namespace dxvk {
         // We do not have to preserve the contents of the
         // buffer if the entire image gets discarded.
         physicalSlice = mappedBuffer->allocPhysicalSlice();
-        physicalSlice.resource()->acquire();
         
         EmitCs([
           cImageBuffer   = mappedBuffer,
           cPhysicalSlice = physicalSlice
         ] (DxvkContext* ctx) {
           ctx->invalidateBuffer(cImageBuffer, cPhysicalSlice);
-          cPhysicalSlice.resource()->release();
         });
       } else {
         // When using any map mode which requires the image contents
@@ -273,9 +276,7 @@ namespace dxvk {
           });
         }
         
-        if (!WaitForResource(mappedBuffer->resource(), MapFlags))
-          return DXGI_ERROR_WAS_STILL_DRAWING;
-        
+        WaitForResource(mappedBuffer->resource(), 0);
         physicalSlice = mappedBuffer->slice();
       }
       
@@ -361,6 +362,7 @@ namespace dxvk {
   
   void D3D11ImmediateContext::EmitCsChunk(Rc<DxvkCsChunk>&& chunk) {
     m_csThread.dispatchChunk(std::move(chunk));
+    m_csIsBusy = true;
   }
   
 }
\ No newline at end of file
diff --git a/src/d3d11/d3d11_context_imm.h b/src/d3d11/d3d11_context_imm.h
index 84dc2c587..18a5b4e77 100644
--- a/src/d3d11/d3d11_context_imm.h
+++ b/src/d3d11/d3d11_context_imm.h
@@ -55,6 +55,7 @@ namespace dxvk {
   private:
     
     DxvkCsThread m_csThread;
+    bool         m_csIsBusy = false;
     
     HRESULT MapBuffer(
             D3D11Buffer*                pResource,
diff --git a/src/dxvk/dxvk_cs.cpp b/src/dxvk/dxvk_cs.cpp
index dd237758e..4aef3ea07 100644
--- a/src/dxvk/dxvk_cs.cpp
+++ b/src/dxvk/dxvk_cs.cpp
@@ -53,19 +53,17 @@ namespace dxvk {
   
   
   void DxvkCsThread::dispatchChunk(Rc<DxvkCsChunk>&& chunk) {
-    { std::unique_lock<std::mutex> lock(m_mutex);
-      m_chunksQueued.push(std::move(chunk));
-      m_chunksPending += 1;
-      
-      if (m_chunksPending > MaxChunksInFlight) {
-        m_condOnSync.wait(lock, [this] {
-          return (m_chunksPending <= MaxChunksInFlight )
-              || (m_stopped.load());
-        });
-      }
+    std::unique_lock<std::mutex> lock(m_mutex);
+    m_chunksPending += 1;
+    m_chunksQueued.push(std::move(chunk));
+    
+    if (m_chunksPending > MaxChunksInFlight) {
+      m_condOnSync.wait(lock, [this] {
+        return (m_chunksPending <= MaxChunksInFlight )
+            || (m_stopped.load());
+      });
     }
     
-    // Wake CS thread
     m_condOnAdd.notify_one();
   }