diff --git a/nac3artiq/src/codegen.rs b/nac3artiq/src/codegen.rs
index 9db031d2..83fa247c 100644
--- a/nac3artiq/src/codegen.rs
+++ b/nac3artiq/src/codegen.rs
@@ -31,7 +31,7 @@ use crate::{symbol_resolver::InnerResolver, timeline::TimeFns};
 
 use inkwell::types::BasicType;
 use itertools::Itertools;
-use nac3core::codegen::classes::{ArrayLikeIndexer, ArrayLikeValue, NDArrayType};
+use nac3core::codegen::classes::{ArrayLikeIndexer, ArrayLikeValue, ArraySliceValue, NDArrayType};
 use nac3core::codegen::llvm_intrinsics;
 use std::{
     collections::{hash_map::DefaultHasher, HashMap},
@@ -552,8 +552,18 @@ fn rpc_codegen_callback_fn<'ctx>(
                 NDArrayType::new(generator, ctx.ctx, ctx.get_llvm_type(generator, elem_ty));
             let llvm_arg = NDArrayValue::from_ptr_val(arg.into_pointer_value(), size_type, None);
 
-            let llvm_usize_sizeof = llvm_arg_ty.size_type().size_of();
-            let llvm_elem_sizeof = llvm_arg_ty.element_type().size_of().unwrap();
+            let llvm_usize_sizeof = ctx
+                .builder
+                .build_int_truncate_or_bit_cast(llvm_arg_ty.size_type().size_of(), int32, "")
+                .unwrap();
+            let llvm_elem_sizeof = ctx
+                .builder
+                .build_int_truncate_or_bit_cast(
+                    llvm_arg_ty.element_type().size_of().unwrap(),
+                    int32,
+                    "",
+                )
+                .unwrap();
 
             let dims_buf_sz =
                 ctx.builder.build_int_mul(llvm_arg.load_ndims(ctx), llvm_usize_sizeof, "").unwrap();
@@ -568,8 +578,8 @@ fn rpc_codegen_callback_fn<'ctx>(
 
             let buffer_size = ctx.builder.build_int_add(dims_buf_sz, data_buf_sz, "").unwrap();
 
-            let buffer =
-                generator.gen_array_var_alloc(ctx, int8.into(), buffer_size, None).unwrap();
+            let buffer = ctx.builder.build_array_alloca(int8, buffer_size, "").unwrap();
+            let buffer = ArraySliceValue::from_ptr_val(buffer, buffer_size, None);
 
             llvm_intrinsics::call_memcpy_generic(
                 ctx,