diff --git a/src/dawn_native/d3d12/TextureCopySplitter.cpp b/src/dawn_native/d3d12/TextureCopySplitter.cpp
index cfa1d1e..f2a8388 100644
--- a/src/dawn_native/d3d12/TextureCopySplitter.cpp
+++ b/src/dawn_native/d3d12/TextureCopySplitter.cpp
@@ -25,6 +25,8 @@
                                      uint32_t offset,
                                      uint32_t bytesPerRow,
                                      uint32_t slicePitch) {
+            ASSERT(bytesPerRow != 0);
+            ASSERT(slicePitch != 0);
             uint32_t byteOffsetX = offset % bytesPerRow;
             offset -= byteOffsetX;
             uint32_t byteOffsetY = offset % slicePitch;
diff --git a/src/dawn_native/d3d12/TextureD3D12.cpp b/src/dawn_native/d3d12/TextureD3D12.cpp
index d9cf9b7..77966b4 100644
--- a/src/dawn_native/d3d12/TextureD3D12.cpp
+++ b/src/dawn_native/d3d12/TextureD3D12.cpp
@@ -823,8 +823,11 @@
             for (uint32_t level = baseMipLevel; level < baseMipLevel + levelCount; ++level) {
                 // compute d3d12 texture copy locations for texture and buffer
                 Extent3D copySize = GetMipLevelVirtualSize(level);
-                TextureCopySplit copySplit = ComputeTextureCopySplit(
-                    {0, 0, 0}, copySize, GetFormat(), uploadHandle.startOffset, bytesPerRow, 0);
+
+                uint32_t rowsPerImage = GetSize().height;
+                TextureCopySplit copySplit =
+                    ComputeTextureCopySplit({0, 0, 0}, copySize, GetFormat(),
+                                            uploadHandle.startOffset, bytesPerRow, rowsPerImage);
 
                 for (uint32_t layer = baseArrayLayer; layer < baseArrayLayer + layerCount;
                      ++layer) {
diff --git a/src/tests/end2end/TextureZeroInitTests.cpp b/src/tests/end2end/TextureZeroInitTests.cpp
index 40962f5..82155cf 100644
--- a/src/tests/end2end/TextureZeroInitTests.cpp
+++ b/src/tests/end2end/TextureZeroInitTests.cpp
@@ -1034,6 +1034,42 @@
     EXPECT_EQ(true, dawn_native::IsTextureSubresourceInitialized(sampleTexture.Get(), 0, 1, 0, 2));
 }
 
+// This is a regression test for crbug.com/dawn/451 where the lazy texture
+// init path on D3D12 had a divide-by-zero exception in the copy split logic.
+TEST_P(TextureZeroInitTest, CopyTextureToBufferNonRenderableUnaligned) {
+    wgpu::TextureDescriptor descriptor;
+    descriptor.size.width = kUnalignedSize;
+    descriptor.size.height = kUnalignedSize;
+    descriptor.size.depth = 1;
+    descriptor.format = wgpu::TextureFormat::R8Snorm;
+    descriptor.usage = wgpu::TextureUsage::CopySrc;
+    wgpu::Texture texture = device.CreateTexture(&descriptor);
+
+    {
+        uint32_t bytesPerRow = Align(kUnalignedSize, kTextureBytesPerRowAlignment);
+
+        wgpu::BufferDescriptor bufferDesc;
+        bufferDesc.size = kUnalignedSize * bytesPerRow;
+        bufferDesc.usage = wgpu::BufferUsage::CopyDst;
+        wgpu::Buffer buffer = device.CreateBuffer(&bufferDesc);
+
+        wgpu::TextureCopyView textureCopyView =
+            utils::CreateTextureCopyView(texture, 0, 0, {0, 0, 0});
+        wgpu::BufferCopyView bufferCopyView =
+            utils::CreateBufferCopyView(buffer, 0, bytesPerRow, 0);
+        wgpu::Extent3D copySize = {kUnalignedSize, kUnalignedSize, 1};
+
+        wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
+        encoder.CopyTextureToBuffer(&textureCopyView, &bufferCopyView, &copySize);
+
+        wgpu::CommandBuffer commands = encoder.Finish();
+        EXPECT_LAZY_CLEAR(1u, queue.Submit(1, &commands));
+    }
+
+    // Expect texture subresource initialized to be true
+    EXPECT_EQ(true, dawn_native::IsTextureSubresourceInitialized(texture.Get(), 0, 1, 0, 1));
+}
+
 DAWN_INSTANTIATE_TEST(
     TextureZeroInitTest,
     D3D12Backend({"nonzero_clear_resources_on_creation_for_testing"}),