diff --git a/src/webgpu/api/operation/command_buffer/image_copy.spec.ts b/src/webgpu/api/operation/command_buffer/image_copy.spec.ts
index f5b11534305f..9f08ffd5e46c 100644
--- a/src/webgpu/api/operation/command_buffer/image_copy.spec.ts
+++ b/src/webgpu/api/operation/command_buffer/image_copy.spec.ts
@@ -1088,16 +1088,19 @@ class ImageCopyTest extends TextureTestMixin(GPUTest) {
 
       // Check the valid data in outputStagingBuffer once per row.
       for (let y = 0; y < copyFromOutputTextureLayout.mipSize[1]; ++y) {
+        const rowOffset = expectedStencilTextureDataBytesPerRow * y;
+        const dataStart = expectedStencilTextureDataOffset +
+                          expectedStencilTextureDataBytesPerRow *
+                            expectedStencilTextureDataRowsPerImage *
+                            stencilTextureLayer +
+                          rowOffset;
         this.expectGPUBufferValuesEqual(
           outputStagingBuffer,
           expectedStencilTextureData.slice(
-            expectedStencilTextureDataOffset +
-              expectedStencilTextureDataBytesPerRow *
-                expectedStencilTextureDataRowsPerImage *
-                stencilTextureLayer +
-              expectedStencilTextureDataBytesPerRow * y,
-            copyFromOutputTextureLayout.mipSize[0]
-          )
+            dataStart,
+            dataStart + copyFromOutputTextureLayout.mipSize[0]
+          ),
+          rowOffset
         );
       }
     }