diff --git a/src/operator/image/image_random.cu b/src/operator/image/image_random.cu
index 79af616c32a7..5dfbbd3b6b00 100644
--- a/src/operator/image/image_random.cu
+++ b/src/operator/image/image_random.cu
@@ -114,7 +114,7 @@ void ToTensorImplCUDA(mshadow::Stream<gpu> *s,
     }
 
     ToTensorCudaKernel<gpu, DType>
-            <<<blocks, dim3(H, cuda::kMaxThreadsPerBlock / H), 0, stream>>>(input, output,
+            <<<blocks, dim3(32, 32), 0, stream>>>(input, output,
                 req, N, H, W, C, normalize_factor);
         MSHADOW_CUDA_POST_KERNEL_CHECK(ToTensorCudaKernel);
 }