diff --git a/backends/vulkan/runtime/graph/ops/impl/ChooseQParams.cpp b/backends/vulkan/runtime/graph/ops/impl/ChooseQParams.cpp
index a36660e0aca..5b8615e0a70 100644
--- a/backends/vulkan/runtime/graph/ops/impl/ChooseQParams.cpp
+++ b/backends/vulkan/runtime/graph/ops/impl/ChooseQParams.cpp
@@ -158,7 +158,8 @@ bool can_use_choose_qparams_per_row(
 void choose_qparams_affine_impl(
     ComputeGraph& graph,
     const std::vector<ValueRef>& args) {
-  int arg_idx = 0;
+  size_t arg_idx = 0;
+  size_t last_arg_idx = args.size() - 1;
   const ValueRef input = args[arg_idx++];
   const ValueRef mapping_type = args[arg_idx++];
   (void)mapping_type;
@@ -170,7 +171,8 @@ void choose_qparams_affine_impl(
   (void)eps;
   const ValueRef scale_dtype = args[arg_idx++];
   const ValueRef zero_point_dtype = args[arg_idx++];
-  const ValueRef out_tuple_ref = args[arg_idx++];
+
+  const ValueRef out_tuple_ref = args[last_arg_idx];
 
   // Suppress unused variable warnings
   (void)target_dtype;
diff --git a/backends/vulkan/runtime/graph/ops/impl/QuantizeDequantize.cpp b/backends/vulkan/runtime/graph/ops/impl/QuantizeDequantize.cpp
index ee8f8a1afb4..8ebbf6dcb99 100644
--- a/backends/vulkan/runtime/graph/ops/impl/QuantizeDequantize.cpp
+++ b/backends/vulkan/runtime/graph/ops/impl/QuantizeDequantize.cpp
@@ -369,7 +369,8 @@ void add_unpack_4w4c_and_dequantize_node(
 void quantize_per_tensor_impl(
     ComputeGraph& graph,
     const std::vector<ValueRef>& args) {
-  int32_t arg_idx = 0;
+  size_t arg_idx = 0;
+  size_t last_arg_idx = args.size() - 1;
   const ValueRef fp_input = args[arg_idx++];
   const ValueRef scale = args[arg_idx++];
   const ValueRef zero_point = args[arg_idx++];
@@ -380,7 +381,7 @@ void quantize_per_tensor_impl(
   const ValueRef dtype = args[arg_idx++];
   (void)dtype;
 
-  const ValueRef int8_output = args[arg_idx++];
+  const ValueRef int8_output = args[last_arg_idx];
 
   VK_CHECK_COND(
       graph.estimate_memory_layout_of(int8_output) == utils::kPackedInt8_4W4C);
@@ -392,7 +393,8 @@ void quantize_per_tensor_impl(
 void dequantize_per_tensor_impl(
     ComputeGraph& graph,
     const std::vector<ValueRef>& args) {
-  int32_t arg_idx = 0;
+  size_t arg_idx = 0;
+  size_t last_arg_idx = args.size() - 1;
   const ValueRef int8_input = args[arg_idx++];
   const ValueRef scale = args[arg_idx++];
   const ValueRef zero_point = args[arg_idx++];
@@ -405,7 +407,7 @@ void dequantize_per_tensor_impl(
   const ValueRef output_dtype = args[arg_idx++];
   (void)output_dtype;
 
-  const ValueRef fp_output = args[arg_idx++];
+  const ValueRef fp_output = args[last_arg_idx];
 
   VK_CHECK_COND(
       graph.estimate_memory_layout_of(int8_input) == utils::kPackedInt8_4W4C);