diff --git a/tutel/custom/custom_kernel.cpp b/tutel/custom/custom_kernel.cpp
index d776cfb..0648539 100644
--- a/tutel/custom/custom_kernel.cpp
+++ b/tutel/custom/custom_kernel.cpp
@@ -463,10 +463,10 @@ static torch::Tensor& nccl_stream_acquire(torch::Tensor &tensor, int idx) {
 static void batch_all_to_all_v(const std::vector<torch::Tensor> &ins, const std::vector<torch::Tensor> &outs, const torch::Tensor &in_sizes_, const torch::Tensor &out_sizes_) {
   AT_ASSERTM(shared_world_size > 0, "Failed to initialize Shared NCCL");
 
-  auto in_sizes_cpu = in_sizes_.to(torch::kCPU).to(torch::kInt32);
-  auto out_sizes_cpu = out_sizes_.to(torch::kCPU).to(torch::kInt32);
-  auto* in_sizes = (unsigned int*)in_sizes_cpu.data_ptr();
-  auto* out_sizes = (unsigned int*)out_sizes_cpu.data_ptr();
+  auto in_sizes_cpu = in_sizes_.to(torch::kCPU).to(torch::kInt64);
+  auto out_sizes_cpu = out_sizes_.to(torch::kCPU).to(torch::kInt64);
+  auto* in_sizes = (unsigned long long*)in_sizes_cpu.data_ptr();
+  auto* out_sizes = (unsigned long long*)out_sizes_cpu.data_ptr();
   auto stream = at::cuda::getCurrentCUDAStream();
 
   for (int k = 0; k < ins.size(); ++k) {
@@ -478,7 +478,7 @@ static void batch_all_to_all_v(const std::vector<torch::Tensor> &ins, const std:
     AT_ASSERTM(size > 0, "Data type of input tensors for batch_all_to_all_v are not recognized.");
     AT_ASSERTM(k == 0 || ins[0].numel() == ins[k].numel(), "Tensor instances within batch_all_to_all_v are supposed to share same length.");
 
-    int in_offset = 0, out_offset = 0;
+    unsigned long long in_offset = 0, out_offset = 0;
     for (int i = 0; i < shared_world_size; ++i) {
       ncclSend((char*)in_buff + in_offset, in_sizes[i] * size, ncclInt8, i, (ncclComm_t)shared_nccl_comm, stream);
       ncclRecv((char*)out_buff + out_offset, out_sizes[i] * size, ncclInt8, i, (ncclComm_t)shared_nccl_comm, stream);
@@ -492,8 +492,8 @@ static void batch_all_to_all_v(const std::vector<torch::Tensor> &ins, const std:
 static void batch_all_gather_v(const std::vector<torch::Tensor> &ins, const std::vector<torch::Tensor> &outs, const torch::Tensor &out_sizes_) {
   AT_ASSERTM(shared_world_size > 0, "Failed to initialize Shared NCCL");
 
-  auto out_sizes_cpu = out_sizes_.to(torch::kCPU).to(torch::kInt32);
-  auto* out_sizes = (unsigned int*)out_sizes_cpu.data_ptr();
+  auto out_sizes_cpu = out_sizes_.to(torch::kCPU).to(torch::kInt64);
+  auto* out_sizes = (unsigned long long*)out_sizes_cpu.data_ptr();
   auto stream = at::cuda::getCurrentCUDAStream();
 
   for (int k = 0; k < ins.size(); ++k) {
@@ -505,7 +505,7 @@ static void batch_all_gather_v(const std::vector<torch::Tensor> &ins, const std:
     AT_ASSERTM(size > 0, "Data type of input tensors for batch_all_gather_v are not recognized.");
     AT_ASSERTM(k == 0 || ins[0].numel() == ins[k].numel(), "Tensor instances within batch_all_gather_v are supposed to share same length.");
 
-    int out_offset = 0;
+    unsigned long long out_offset = 0;
     for (int i = 0; i < shared_world_size; ++i) {
       if (out_sizes[shared_world_rank])
         ncclSend((char*)in_buff, out_sizes[shared_world_rank] * size, ncclInt8, i, (ncclComm_t)shared_nccl_comm, stream);
diff --git a/tutel/examples/nccl_all_to_all_v.py b/tutel/examples/nccl_all_to_all_v.py
index fcfcc51..92311ef 100755
--- a/tutel/examples/nccl_all_to_all_v.py
+++ b/tutel/examples/nccl_all_to_all_v.py
@@ -12,10 +12,10 @@
 
 if parallel_env.global_rank == 0:
   input = torch.tensor([10, 10, 10, 10, 10], device=local_device)
-  send_counts = torch.tensor([1, 4], dtype=torch.int32, device=local_device)
+  send_counts = torch.tensor([1, 4], dtype=torch.int64, device=local_device)
 else:
   input = torch.tensor([20, 20, 20], device=local_device)
-  send_counts = torch.tensor([2, 1], dtype=torch.int32, device=local_device)
+  send_counts = torch.tensor([2, 1], dtype=torch.int64, device=local_device)
 
 print(f'Device-{parallel_env.global_rank} sends: {[input,]}')
 
diff --git a/tutel/impls/communicate.py b/tutel/impls/communicate.py
index 4c75d0d..9b9543d 100644
--- a/tutel/impls/communicate.py
+++ b/tutel/impls/communicate.py
@@ -211,7 +211,9 @@ def batch_all_to_all_v(datas, partition_sizes, group=None):
     assert type(datas) in (tuple, list), "data type for batch_all_to_all_v() is not a list of tensors"
     in_sizes = partition_sizes
     if type(in_sizes) != torch.Tensor:
-        in_sizes = torch.tensor(in_sizes, dtype=torch.int32, device=datas[0].device)
+        in_sizes = torch.tensor(in_sizes, dtype=torch.int64, device=datas[0].device)
+    else:
+        in_sizes = in_sizes.to(torch.int64)
     world_size = get_world_size(group)
     assert in_sizes.numel() == world_size
     if world_size == 1: