diff --git a/csrc/kernels.cu b/csrc/kernels.cu
index e0df802..e1ec00d 100644
--- a/csrc/kernels.cu
+++ b/csrc/kernels.cu
@@ -1260,6 +1260,7 @@ kPreconditionOptimizerStatic8bit1State(T* p, T* __restrict__ const g, unsigned c
 
 template<typename T, int OPTIMIZER>
 __global__ void
+__launch_bounds__(1024, 1)
 kOptimizerStatic8bit1State(T* p, T* const g, unsigned char* state1,
                 const float *unorm, const float max_unorm, const float param_norm,
                 const float beta1, const float beta2,