diff --git a/candle-nn/src/layer_norm.rs b/candle-nn/src/layer_norm.rs
index 65cd17292c..c7ef0bf5fb 100644
--- a/candle-nn/src/layer_norm.rs
+++ b/candle-nn/src/layer_norm.rs
@@ -145,7 +145,7 @@ impl crate::Module for LayerNorm {
 #[cfg(feature = "cuda")]
 impl crate::Module for LayerNorm {
     fn forward(&self, x: &Tensor) -> Result<Tensor> {
-        const K_CUDABLOCK_REDUCE_NUM_THREADS: i32 = 512;
+        const K_CUDABLOCK_REDUCE_NUM_THREADS: u32 = 512;
         let cuda_dev = match x.device() {
             Device::Cpu | Device::Metal(_) => return self.forward_slow(x),
             Device::Cuda(dev) => dev
@@ -171,7 +171,7 @@ impl crate::Module for LayerNorm {
         }.slice;
 
         let cfg_1 = LaunchConfig {
-            grid_dim: (m,1,1),
+            grid_dim: (m as u32,1,1),
             block_dim: (K_CUDABLOCK_REDUCE_NUM_THREADS,1,1),
             shared_mem_bytes: 0,
         };