diff --git a/nac3core/src/codegen/irrt/irrt.c b/nac3core/src/codegen/irrt/irrt.c
index 1436447b..a53bf07c 100644
--- a/nac3core/src/codegen/irrt/irrt.c
+++ b/nac3core/src/codegen/irrt/irrt.c
@@ -201,7 +201,7 @@ double __nac3_j0(double x) {
 }
 
 uint32_t __nac3_ndarray_calc_size(
-    const uint64_t *list_data,
+    const uint32_t *list_data,
     uint32_t list_len,
     uint32_t begin_idx,
     uint32_t end_idx
@@ -210,7 +210,7 @@ uint32_t __nac3_ndarray_calc_size(
 
     uint32_t num_elems = 1;
     for (uint32_t i = begin_idx; i < end_idx; ++i) {
-        uint64_t val = list_data[i];
+        uint32_t val = list_data[i];
         __builtin_assume(val > 0);
         num_elems *= val;
     }
diff --git a/nac3core/src/codegen/irrt/mod.rs b/nac3core/src/codegen/irrt/mod.rs
index 8677f085..8bab9854 100644
--- a/nac3core/src/codegen/irrt/mod.rs
+++ b/nac3core/src/codegen/irrt/mod.rs
@@ -579,10 +579,8 @@ where
     G: CodeGenerator + ?Sized,
     Dims: ArrayLikeIndexer<'ctx>,
 {
-    let llvm_i64 = ctx.ctx.i64_type();
     let llvm_usize = generator.get_size_type(ctx.ctx);
-
-    let llvm_pi64 = llvm_i64.ptr_type(AddressSpace::default());
+    let llvm_pusize = llvm_usize.ptr_type(AddressSpace::default());
 
     let ndarray_calc_size_fn_name = match llvm_usize.get_bit_width() {
         32 => "__nac3_ndarray_calc_size",
@@ -590,7 +588,7 @@ where
         bw => unreachable!("Unsupported size type bit width: {}", bw),
     };
     let ndarray_calc_size_fn_t = llvm_usize.fn_type(
-        &[llvm_pi64.into(), llvm_usize.into(), llvm_usize.into(), llvm_usize.into()],
+        &[llvm_pusize.into(), llvm_usize.into(), llvm_usize.into(), llvm_usize.into()],
         false,
     );
     let ndarray_calc_size_fn =