diff --git a/src/dawn_native/d3d12/BindGroupD3D12.cpp b/src/dawn_native/d3d12/BindGroupD3D12.cpp
index e4591ac883..4d27b521bf 100644
--- a/src/dawn_native/d3d12/BindGroupD3D12.cpp
+++ b/src/dawn_native/d3d12/BindGroupD3D12.cpp
@@ -180,10 +180,10 @@ namespace dawn_native { namespace d3d12 {
             }
 
             d3d12Device->CopyDescriptorsSimple(
-                viewDescriptorCount, viewDescriptorHeapAllocation.GetCPUHandle(0),
-                mCPUViewAllocation.OffsetFrom(0, 0), D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV);
+                viewDescriptorCount, viewDescriptorHeapAllocation.GetBaseCPUDescriptor(),
+                mCPUViewAllocation.GetBaseDescriptor(), D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV);
 
-            mBaseViewDescriptor = viewDescriptorHeapAllocation.GetGPUHandle(0);
+            mBaseViewDescriptor = viewDescriptorHeapAllocation.GetBaseGPUDescriptor();
         }
 
         const uint32_t samplerDescriptorCount = bgl->GetSamplerDescriptorCount();
@@ -197,10 +197,10 @@ namespace dawn_native { namespace d3d12 {
             }
 
             d3d12Device->CopyDescriptorsSimple(
-                samplerDescriptorCount, samplerDescriptorHeapAllocation.GetCPUHandle(0),
-                mCPUSamplerAllocation.OffsetFrom(0, 0), D3D12_DESCRIPTOR_HEAP_TYPE_SAMPLER);
+                samplerDescriptorCount, samplerDescriptorHeapAllocation.GetBaseCPUDescriptor(),
+                mCPUSamplerAllocation.GetBaseDescriptor(), D3D12_DESCRIPTOR_HEAP_TYPE_SAMPLER);
 
-            mBaseSamplerDescriptor = samplerDescriptorHeapAllocation.GetGPUHandle(0);
+            mBaseSamplerDescriptor = samplerDescriptorHeapAllocation.GetBaseGPUDescriptor();
         }
 
         // Record both the device and heap serials to determine later if the allocations are still
diff --git a/src/dawn_native/d3d12/CPUDescriptorHeapAllocationD3D12.cpp b/src/dawn_native/d3d12/CPUDescriptorHeapAllocationD3D12.cpp
index 635b25ebc7..021c47ab87 100644
--- a/src/dawn_native/d3d12/CPUDescriptorHeapAllocationD3D12.cpp
+++ b/src/dawn_native/d3d12/CPUDescriptorHeapAllocationD3D12.cpp
@@ -23,6 +23,11 @@ namespace dawn_native { namespace d3d12 {
         : mBaseDescriptor(baseDescriptor), mHeapIndex(heapIndex) {
     }
 
+    D3D12_CPU_DESCRIPTOR_HANDLE CPUDescriptorHeapAllocation::GetBaseDescriptor() const {
+        ASSERT(IsValid());
+        return mBaseDescriptor;
+    }
+
     D3D12_CPU_DESCRIPTOR_HANDLE CPUDescriptorHeapAllocation::OffsetFrom(
         uint32_t sizeIncrementInBytes,
         uint32_t offsetInDescriptorCount) const {
diff --git a/src/dawn_native/d3d12/CPUDescriptorHeapAllocationD3D12.h b/src/dawn_native/d3d12/CPUDescriptorHeapAllocationD3D12.h
index 560c99871e..05aaf5185b 100644
--- a/src/dawn_native/d3d12/CPUDescriptorHeapAllocationD3D12.h
+++ b/src/dawn_native/d3d12/CPUDescriptorHeapAllocationD3D12.h
@@ -27,6 +27,8 @@ namespace dawn_native { namespace d3d12 {
         CPUDescriptorHeapAllocation() = default;
         CPUDescriptorHeapAllocation(D3D12_CPU_DESCRIPTOR_HANDLE baseDescriptor, uint32_t heapIndex);
 
+        D3D12_CPU_DESCRIPTOR_HANDLE GetBaseDescriptor() const;
+
         D3D12_CPU_DESCRIPTOR_HANDLE OffsetFrom(uint32_t sizeIncrementInBytes,
                                                uint32_t offsetInDescriptorCount) const;
         uint32_t GetHeapIndex() const;
diff --git a/src/dawn_native/d3d12/DescriptorHeapAllocationD3D12.cpp b/src/dawn_native/d3d12/DescriptorHeapAllocationD3D12.cpp
index fd16f1ef58..2ca7885299 100644
--- a/src/dawn_native/d3d12/DescriptorHeapAllocationD3D12.cpp
+++ b/src/dawn_native/d3d12/DescriptorHeapAllocationD3D12.cpp
@@ -17,30 +17,21 @@
 
 namespace dawn_native { namespace d3d12 {
 
-    DescriptorHeapAllocation::DescriptorHeapAllocation() : mSizeIncrement(0) {
-    }
-
     DescriptorHeapAllocation::DescriptorHeapAllocation(
-        uint32_t sizeIncrement,
         D3D12_CPU_DESCRIPTOR_HANDLE baseCPUDescriptorHandle,
         D3D12_GPU_DESCRIPTOR_HANDLE baseGPUDescriptorHandle)
-        : mSizeIncrement(sizeIncrement),
-          mBaseCPUDescriptorHandle(baseCPUDescriptorHandle),
+        : mBaseCPUDescriptorHandle(baseCPUDescriptorHandle),
           mBaseGPUDescriptorHandle(baseGPUDescriptorHandle) {
     }
 
-    D3D12_CPU_DESCRIPTOR_HANDLE DescriptorHeapAllocation::GetCPUHandle(uint32_t offset) const {
+    D3D12_GPU_DESCRIPTOR_HANDLE DescriptorHeapAllocation::GetBaseGPUDescriptor() const {
         ASSERT(!IsInvalid());
-        D3D12_CPU_DESCRIPTOR_HANDLE cpuHandle = mBaseCPUDescriptorHandle;
-        cpuHandle.ptr += mSizeIncrement * offset;
-        return cpuHandle;
+        return mBaseGPUDescriptorHandle;
     }
 
-    D3D12_GPU_DESCRIPTOR_HANDLE DescriptorHeapAllocation::GetGPUHandle(uint32_t offset) const {
+    D3D12_CPU_DESCRIPTOR_HANDLE DescriptorHeapAllocation::GetBaseCPUDescriptor() const {
         ASSERT(!IsInvalid());
-        D3D12_GPU_DESCRIPTOR_HANDLE gpuHandle = mBaseGPUDescriptorHandle;
-        gpuHandle.ptr += mSizeIncrement * offset;
-        return gpuHandle;
+        return mBaseCPUDescriptorHandle;
     }
 
     bool DescriptorHeapAllocation::IsInvalid() const {
diff --git a/src/dawn_native/d3d12/DescriptorHeapAllocationD3D12.h b/src/dawn_native/d3d12/DescriptorHeapAllocationD3D12.h
index 30a034c9cc..e63d415b31 100644
--- a/src/dawn_native/d3d12/DescriptorHeapAllocationD3D12.h
+++ b/src/dawn_native/d3d12/DescriptorHeapAllocationD3D12.h
@@ -21,23 +21,20 @@
 
 namespace dawn_native { namespace d3d12 {
 
-    // Wrapper for a handle into a descriptor heap.
+    // Wrapper for a handle into a GPU-only descriptor heap.
     class DescriptorHeapAllocation {
       public:
-        DescriptorHeapAllocation();
-        DescriptorHeapAllocation(uint32_t sizeIncrement,
-                                 D3D12_CPU_DESCRIPTOR_HANDLE baseCPUDescriptorHandle,
+        DescriptorHeapAllocation() = default;
+        DescriptorHeapAllocation(D3D12_CPU_DESCRIPTOR_HANDLE baseCPUDescriptorHandle,
                                  D3D12_GPU_DESCRIPTOR_HANDLE baseGPUDescriptorHandle);
         ~DescriptorHeapAllocation() = default;
 
-        D3D12_CPU_DESCRIPTOR_HANDLE GetCPUHandle(uint32_t offset) const;
-        D3D12_GPU_DESCRIPTOR_HANDLE GetGPUHandle(uint32_t offset) const;
+        D3D12_GPU_DESCRIPTOR_HANDLE GetBaseGPUDescriptor() const;
+        D3D12_CPU_DESCRIPTOR_HANDLE GetBaseCPUDescriptor() const;
 
         bool IsInvalid() const;
 
       private:
-        uint32_t mSizeIncrement;
-
         D3D12_CPU_DESCRIPTOR_HANDLE mBaseCPUDescriptorHandle = {0};
         D3D12_GPU_DESCRIPTOR_HANDLE mBaseGPUDescriptorHandle = {0};
     };
diff --git a/src/dawn_native/d3d12/ShaderVisibleDescriptorAllocatorD3D12.cpp b/src/dawn_native/d3d12/ShaderVisibleDescriptorAllocatorD3D12.cpp
index 101ca4b190..d881f26fce 100644
--- a/src/dawn_native/d3d12/ShaderVisibleDescriptorAllocatorD3D12.cpp
+++ b/src/dawn_native/d3d12/ShaderVisibleDescriptorAllocatorD3D12.cpp
@@ -101,16 +101,20 @@ namespace dawn_native { namespace d3d12 {
 
         ID3D12DescriptorHeap* descriptorHeap = mShaderVisibleBuffers[heapType].heap.Get();
 
-        D3D12_CPU_DESCRIPTOR_HANDLE baseCPUDescriptor =
-            descriptorHeap->GetCPUDescriptorHandleForHeapStart();
-        baseCPUDescriptor.ptr += mSizeIncrements[heapType] * startOffset;
+        const uint64_t heapOffset = mSizeIncrements[heapType] * startOffset;
 
-        D3D12_GPU_DESCRIPTOR_HANDLE baseGPUDescriptor =
-            descriptorHeap->GetGPUDescriptorHandleForHeapStart();
-        baseGPUDescriptor.ptr += mSizeIncrements[heapType] * startOffset;
+        // Check for 32-bit overflow since CPU heap start handle uses size_t.
+        const size_t cpuHeapStartPtr = descriptorHeap->GetCPUDescriptorHandleForHeapStart().ptr;
 
-        return DescriptorHeapAllocation{mSizeIncrements[heapType], baseCPUDescriptor,
-                                        baseGPUDescriptor};
+        ASSERT(heapOffset <= std::numeric_limits<size_t>::max() - cpuHeapStartPtr);
+
+        const D3D12_CPU_DESCRIPTOR_HANDLE baseCPUDescriptor = {cpuHeapStartPtr +
+                                                               static_cast<size_t>(heapOffset)};
+
+        const D3D12_GPU_DESCRIPTOR_HANDLE baseGPUDescriptor = {
+            descriptorHeap->GetGPUDescriptorHandleForHeapStart().ptr + heapOffset};
+
+        return DescriptorHeapAllocation{baseCPUDescriptor, baseGPUDescriptor};
     }
 
     std::array<ID3D12DescriptorHeap*, 2> ShaderVisibleDescriptorAllocator::GetShaderVisibleHeaps()