diff --git a/mlx/backend/cuda/custom_kernel.cpp b/mlx/backend/cuda/custom_kernel.cpp
index 2f8be9221..5ce9d3097 100644
--- a/mlx/backend/cuda/custom_kernel.cpp
+++ b/mlx/backend/cuda/custom_kernel.cpp
@@ -352,7 +352,7 @@ void CustomKernel::eval_gpu(
   // Make the grid
   const auto [tx, ty, tz] = threadgroup_;
   const auto [gx, gy, gz] = grid_;
-  dim3 block(tx, ty, tz);
+  dim3 block(std::min(tx, gx), std::min(ty, gy), std::min(tz, gz));
   dim3 grid((gx + tx - 1) / tx, (gy + ty - 1) / ty, (gz + tz - 1) / tz);
 
   // Call the kernel