diff --git a/nac3artiq/src/codegen.rs b/nac3artiq/src/codegen.rs
index ebe146fb7..38d9ecd3e 100644
--- a/nac3artiq/src/codegen.rs
+++ b/nac3artiq/src/codegen.rs
@@ -1,18 +1,19 @@
 use nac3core::{
     codegen::{expr::gen_call, stmt::gen_with, CodeGenContext, CodeGenerator},
+    symbol_resolver::ValueEnum,
     toplevel::DefinitionId,
     typecheck::typedef::{FunSignature, Type},
-    symbol_resolver::ValueEnum,
 };
 
 use nac3parser::ast::{Expr, ExprKind, Located, Stmt, StmtKind, StrRef};
 
-use inkwell::values::BasicValueEnum;
+use inkwell::{context::Context, types::IntType, values::BasicValueEnum};
 
 use crate::timeline::TimeFns;
 
 pub struct ArtiqCodeGenerator<'a> {
     name: String,
+    size_t: u32,
     name_counter: u32,
     start: Option<Expr<Option<Type>>>,
     end: Option<Expr<Option<Type>>>,
@@ -20,9 +21,11 @@ pub struct ArtiqCodeGenerator<'a> {
 }
 
 impl<'a> ArtiqCodeGenerator<'a> {
-    pub fn new(name: String, timeline: &'a (dyn TimeFns + Sync)) -> ArtiqCodeGenerator<'a> {
+    pub fn new(name: String, size_t: u32, timeline: &'a (dyn TimeFns + Sync)) -> ArtiqCodeGenerator<'a> {
+        assert!(size_t == 32 || size_t == 64);
         ArtiqCodeGenerator {
             name,
+            size_t,
             name_counter: 0,
             start: None,
             end: None,
@@ -36,6 +39,14 @@ impl<'b> CodeGenerator for ArtiqCodeGenerator<'b> {
         &self.name
     }
 
+    fn get_size_type<'ctx>(&self, ctx: &'ctx Context) -> IntType<'ctx> {
+        if self.size_t == 32 {
+            ctx.i32_type()
+        } else {
+            ctx.i64_type()
+        }
+    }
+
     fn gen_call<'ctx, 'a>(
         &mut self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
@@ -45,7 +56,7 @@ impl<'b> CodeGenerator for ArtiqCodeGenerator<'b> {
     ) -> Option<BasicValueEnum<'ctx>> {
         let result = gen_call(self, ctx, obj, fun, params);
         if let Some(end) = self.end.clone() {
-            let old_end = self.gen_expr(ctx, &end).unwrap().to_basic_value_enum(ctx);
+            let old_end = self.gen_expr(ctx, &end).unwrap().to_basic_value_enum(ctx, self);
             let now = self.timeline.emit_now_mu(ctx);
             let smax = ctx.module.get_function("llvm.smax.i64").unwrap_or_else(|| {
                 let i64 = ctx.ctx.i64_type();
@@ -65,7 +76,7 @@ impl<'b> CodeGenerator for ArtiqCodeGenerator<'b> {
             ctx.builder.build_store(end_store, max);
         }
         if let Some(start) = self.start.clone() {
-            let start_val = self.gen_expr(ctx, &start).unwrap().to_basic_value_enum(ctx);
+            let start_val = self.gen_expr(ctx, &start).unwrap().to_basic_value_enum(ctx, self);
             self.timeline.emit_at_mu(ctx, start_val);
         }
         result
@@ -97,7 +108,9 @@ impl<'b> CodeGenerator for ArtiqCodeGenerator<'b> {
                         let old_start = self.start.take();
                         let old_end = self.end.take();
                         let now = if let Some(old_start) = &old_start {
-                            self.gen_expr(ctx, old_start).unwrap().to_basic_value_enum(ctx)
+                            self.gen_expr(ctx, old_start)
+                                .unwrap()
+                                .to_basic_value_enum(ctx, self)
                         } else {
                             self.timeline.emit_now_mu(ctx)
                         };
@@ -146,7 +159,10 @@ impl<'b> CodeGenerator for ArtiqCodeGenerator<'b> {
                         }
                         // set duration
                         let end_expr = self.end.take().unwrap();
-                        let end_val = self.gen_expr(ctx, &end_expr).unwrap().to_basic_value_enum(ctx);
+                        let end_val = self
+                            .gen_expr(ctx, &end_expr)
+                            .unwrap()
+                            .to_basic_value_enum(ctx, self);
 
                         // inside an sequential block
                         if old_start.is_none() {
@@ -154,15 +170,19 @@ impl<'b> CodeGenerator for ArtiqCodeGenerator<'b> {
                         }
                         // inside a parallel block, should update the outer max now_mu
                         if let Some(old_end) = &old_end {
-                            let outer_end_val = self.gen_expr(ctx, old_end).unwrap().to_basic_value_enum(ctx);
-                            let smax = ctx.module.get_function("llvm.smax.i64").unwrap_or_else(|| {
-                                let i64 = ctx.ctx.i64_type();
-                                ctx.module.add_function(
-                                    "llvm.smax.i64",
-                                    i64.fn_type(&[i64.into(), i64.into()], false),
-                                    None,
-                                )
-                            });
+                            let outer_end_val = self
+                                .gen_expr(ctx, old_end)
+                                .unwrap()
+                                .to_basic_value_enum(ctx, self);
+                            let smax =
+                                ctx.module.get_function("llvm.smax.i64").unwrap_or_else(|| {
+                                    let i64 = ctx.ctx.i64_type();
+                                    ctx.module.add_function(
+                                        "llvm.smax.i64",
+                                        i64.fn_type(&[i64.into(), i64.into()], false),
+                                        None,
+                                    )
+                                });
                             let max = ctx
                                 .builder
                                 .build_call(smax, &[end_val.into(), outer_end_val.into()], "smax")
diff --git a/nac3artiq/src/lib.rs b/nac3artiq/src/lib.rs
index c085ba8ca..c337320f9 100644
--- a/nac3artiq/src/lib.rs
+++ b/nac3artiq/src/lib.rs
@@ -558,10 +558,15 @@ impl Nac3 {
             let buffer = buffer.as_slice().into();
             membuffer.lock().push(buffer);
         })));
+        let size_t = if self.isa == Isa::Host {
+            64
+        } else {
+            32
+        };
         let thread_names: Vec<String> = (0..4).map(|_| "main".to_string()).collect();
         let threads: Vec<_> = thread_names
             .iter()
-            .map(|s| Box::new(ArtiqCodeGenerator::new(s.to_string(), self.time_fns)))
+            .map(|s| Box::new(ArtiqCodeGenerator::new(s.to_string(), size_t, self.time_fns)))
             .collect();
 
         py.allow_threads(|| {
diff --git a/nac3artiq/src/symbol_resolver.rs b/nac3artiq/src/symbol_resolver.rs
index e42db752a..303860702 100644
--- a/nac3artiq/src/symbol_resolver.rs
+++ b/nac3artiq/src/symbol_resolver.rs
@@ -1,6 +1,6 @@
 use inkwell::{types::BasicType, values::BasicValueEnum, AddressSpace};
 use nac3core::{
-    codegen::CodeGenContext,
+    codegen::{CodeGenContext, CodeGenerator},
     location::Location,
     symbol_resolver::{StaticValue, SymbolResolver, SymbolValue, ValueEnum},
     toplevel::{DefinitionId, TopLevelDef},
@@ -72,6 +72,7 @@ impl StaticValue for PythonValue {
     fn to_basic_value_enum<'ctx, 'a>(
         &self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
+        generator: &mut dyn CodeGenerator,
     ) -> BasicValueEnum<'ctx> {
         if let Some(val) = self.resolver.id_to_primitive.read().get(&self.id) {
             return match val {
@@ -89,7 +90,7 @@ impl StaticValue for PythonValue {
 
         Python::with_gil(|py| -> PyResult<BasicValueEnum<'ctx>> {
             self.resolver
-                .get_obj_value(py, self.value.as_ref(py), ctx)
+                .get_obj_value(py, self.value.as_ref(py), ctx, generator)
                 .map(Option::unwrap)
         })
         .unwrap()
@@ -540,6 +541,7 @@ impl InnerResolver {
         py: Python,
         obj: &PyAny,
         ctx: &mut CodeGenContext<'ctx, 'a>,
+        generator: &mut dyn CodeGenerator,
     ) -> PyResult<Option<BasicValueEnum<'ctx>>> {
         let ty_id: u64 = self
             .helper
@@ -595,11 +597,9 @@ impl InnerResolver {
                 .unwrap()
             };
             let ty = ctx.get_llvm_type(ty);
+            let size_t = generator.get_size_type(ctx.ctx);
             let arr_ty = ctx.ctx.struct_type(
-                &[
-                    ctx.ctx.i32_type().into(),
-                    ty.ptr_type(AddressSpace::Generic).into(),
-                ],
+                &[ty.ptr_type(AddressSpace::Generic).into(), size_t.into()],
                 false,
             );
 
@@ -618,7 +618,7 @@ impl InnerResolver {
             let arr: Result<Option<Vec<_>>, _> = (0..len)
                 .map(|i| {
                     obj.get_item(i)
-                        .and_then(|elem| self.get_obj_value(py, elem, ctx))
+                        .and_then(|elem| self.get_obj_value(py, elem, ctx, generator))
                 })
                 .collect();
             let arr = arr?.unwrap();
@@ -665,11 +665,11 @@ impl InnerResolver {
             arr_global.set_initializer(&arr);
 
             let val = arr_ty.const_named_struct(&[
-                ctx.ctx.i32_type().const_int(len as u64, false).into(),
                 arr_global
                     .as_pointer_value()
                     .const_cast(ty.ptr_type(AddressSpace::Generic))
                     .into(),
+                size_t.const_int(len as u64, false).into(),
             ]);
 
             let global = ctx
@@ -716,7 +716,7 @@ impl InnerResolver {
 
             let val: Result<Option<Vec<_>>, _> = elements
                 .iter()
-                .map(|elem| self.get_obj_value(py, elem, ctx))
+                .map(|elem| self.get_obj_value(py, elem, ctx, generator))
                 .collect();
             let val = val?.unwrap();
             let val = ctx.ctx.const_struct(&val, false);
@@ -763,7 +763,7 @@ impl InnerResolver {
                 let values: Result<Option<Vec<_>>, _> = fields
                     .iter()
                     .map(|(name, _, _)| {
-                        self.get_obj_value(py, obj.getattr(&name.to_string())?, ctx)
+                        self.get_obj_value(py, obj.getattr(&name.to_string())?, ctx, generator)
                     })
                     .collect();
                 let values = values?;
diff --git a/nac3core/src/codegen/expr.rs b/nac3core/src/codegen/expr.rs
index a4363f551..69c2423a6 100644
--- a/nac3core/src/codegen/expr.rs
+++ b/nac3core/src/codegen/expr.rs
@@ -35,12 +35,9 @@ pub fn get_subst_key(
         })
         .unwrap_or_default();
     vars.extend(fun_vars.iter());
-    let sorted =
-        vars.keys().filter(|id| filter.map(|v| v.contains(id)).unwrap_or(true)).sorted();
+    let sorted = vars.keys().filter(|id| filter.map(|v| v.contains(id)).unwrap_or(true)).sorted();
     sorted
-        .map(|id| {
-            unifier.stringify(vars[id], &mut |id| id.to_string(), &mut |id| id.to_string())
-        })
+        .map(|id| unifier.stringify(vars[id], &mut |id| id.to_string(), &mut |id| id.to_string()))
         .join(", ")
 }
 
@@ -104,8 +101,19 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
         }
     }
 
-    pub fn get_llvm_type(&mut self, ty: Type) -> BasicTypeEnum<'ctx> {
-        get_llvm_type(self.ctx, &mut self.unifier, self.top_level, &mut self.type_cache, ty)
+    pub fn get_llvm_type(
+        &mut self,
+        generator: &mut dyn CodeGenerator,
+        ty: Type,
+    ) -> BasicTypeEnum<'ctx> {
+        get_llvm_type(
+            self.ctx,
+            generator,
+            &mut self.unifier,
+            self.top_level,
+            &mut self.type_cache,
+            ty,
+        )
     }
 
     fn gen_const(&mut self, value: &Constant, ty: Type) -> BasicValueEnum<'ctx> {
@@ -223,7 +231,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
     }
 }
 
-pub fn gen_constructor<'ctx, 'a, G: CodeGenerator + ?Sized>(
+pub fn gen_constructor<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
     signature: &FunSignature,
@@ -239,7 +247,7 @@ pub fn gen_constructor<'ctx, 'a, G: CodeGenerator + ?Sized>(
                     fun_id = Some(*id);
                 }
             }
-            let ty = ctx.get_llvm_type(signature.ret).into_pointer_type();
+            let ty = ctx.get_llvm_type(generator, signature.ret).into_pointer_type();
             let zelf_ty: BasicTypeEnum = ty.get_element_type().try_into().unwrap();
             let zelf: BasicValueEnum<'ctx> = ctx.builder.build_alloca(zelf_ty, "alloca").into();
             // call `__init__` if there is one
@@ -328,7 +336,7 @@ pub fn gen_func_instance<'ctx, 'a>(
     }
 }
 
-pub fn gen_call<'ctx, 'a, G: CodeGenerator + ?Sized>(
+pub fn gen_call<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
     obj: Option<(Type, ValueEnum<'ctx>)>,
@@ -352,10 +360,10 @@ pub fn gen_call<'ctx, 'a, G: CodeGenerator + ?Sized>(
             } => {
                 if let Some(callback) = codegen_callback {
                     // TODO: Change signature
-                    let obj = obj.map(|(t, v)| (t, v.to_basic_value_enum(ctx)));
+                    let obj = obj.map(|(t, v)| (t, v.to_basic_value_enum(ctx, generator)));
                     let params = params
                         .into_iter()
-                        .map(|(name, val)| (name, val.to_basic_value_enum(ctx)))
+                        .map(|(name, val)| (name, val.to_basic_value_enum(ctx, generator)))
                         .collect();
                     return callback.run(ctx, obj, fun, params);
                 }
@@ -409,8 +417,10 @@ pub fn gen_call<'ctx, 'a, G: CodeGenerator + ?Sized>(
                 } else {
                     format!("{}:{}", id, old_key)
                 };
-                param_vals =
-                    real_params.into_iter().map(|p| p.to_basic_value_enum(ctx).into()).collect_vec();
+                param_vals = real_params
+                    .into_iter()
+                    .map(|p| p.to_basic_value_enum(ctx, generator).into())
+                    .collect_vec();
                 instance_to_symbol.get(&key).cloned()
             }
             TopLevelDef::Class { .. } => {
@@ -426,11 +436,11 @@ pub fn gen_call<'ctx, 'a, G: CodeGenerator + ?Sized>(
         if let Some(obj) = &obj {
             args.insert(0, FuncArg { name: "self".into(), ty: obj.0, default_value: None });
         }
-        let params = args.iter().map(|arg| ctx.get_llvm_type(arg.ty).into()).collect_vec();
+        let params = args.iter().map(|arg| ctx.get_llvm_type(generator, arg.ty).into()).collect_vec();
         let fun_ty = if ctx.unifier.unioned(fun.0.ret, ctx.primitives.none) {
             ctx.ctx.void_type().fn_type(&params, false)
         } else {
-            ctx.get_llvm_type(fun.0.ret).fn_type(&params, false)
+            ctx.get_llvm_type(generator, fun.0.ret).fn_type(&params, false)
         };
         ctx.module.add_function(&symbol, fun_ty, None)
     });
@@ -454,32 +464,36 @@ pub fn destructure_range<'ctx, 'a>(
     (start, end, step)
 }
 
-pub fn allocate_list<'ctx, 'a>(
+pub fn allocate_list<'ctx, 'a, G: CodeGenerator>(
+    generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
     ty: BasicTypeEnum<'ctx>,
     length: IntValue<'ctx>,
 ) -> PointerValue<'ctx> {
     let arr_ptr = ctx.builder.build_array_alloca(ty, length, "tmparr");
-    let arr_ty = ctx.ctx.struct_type(
-        &[ctx.ctx.i32_type().into(), ty.ptr_type(AddressSpace::Generic).into()],
-        false,
-    );
+    let size_t = generator.get_size_type(ctx.ctx);
+    let i32_t = ctx.ctx.i32_type();
+    let arr_ty =
+        ctx.ctx.struct_type(&[ty.ptr_type(AddressSpace::Generic).into(), size_t.into()], false);
     let zero = ctx.ctx.i32_type().const_zero();
     let arr_str_ptr = ctx.builder.build_alloca(arr_ty, "tmparrstr");
     unsafe {
-        let len_ptr = ctx.builder.build_in_bounds_gep(arr_str_ptr, &[zero, zero], "len_ptr");
-        ctx.builder.build_store(len_ptr, length);
-        let ptr_to_arr = ctx.builder.build_in_bounds_gep(
+        let len_ptr = ctx.builder.build_in_bounds_gep(
             arr_str_ptr,
-            &[zero, ctx.ctx.i32_type().const_int(1, false)],
-            "ptr_to_arr",
+            &[zero, i32_t.const_int(1, false)],
+            "len_ptr",
         );
+        let length = ctx.builder.build_int_z_extend(length, size_t, "zext");
+        ctx.builder.build_store(len_ptr, length);
+        let ptr_to_arr =
+            ctx.builder.build_in_bounds_gep(arr_str_ptr, &[zero, i32_t.const_zero()], "ptr_to_arr");
         ctx.builder.build_store(ptr_to_arr, arr_ptr);
+        println!("arr_str_ptr: {:?}", arr_str_ptr);
         arr_str_ptr
     }
 }
 
-pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator + ?Sized>(
+pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
     expr: &Expr<Option<Type>>,
@@ -491,15 +505,16 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator + ?Sized>(
         let cont_bb = ctx.ctx.append_basic_block(current, "cont");
 
         let Comprehension { target, iter, ifs, .. } = &generators[0];
-        let iter_val = generator.gen_expr(ctx, iter).unwrap().to_basic_value_enum(ctx);
+        let iter_val = generator.gen_expr(ctx, iter).unwrap().to_basic_value_enum(ctx, generator);
         let int32 = ctx.ctx.i32_type();
-        let zero = int32.const_zero();
+        let size_t = generator.get_size_type(ctx.ctx);
+        let zero = size_t.const_zero();
 
-        let index = generator.gen_var_alloc(ctx, ctx.primitives.int32);
+        let index = generator.gen_var_alloc(ctx, size_t.into());
         // counter = -1
-        ctx.builder.build_store(index, ctx.ctx.i32_type().const_zero());
+        ctx.builder.build_store(index, size_t.const_zero());
 
-        let elem_ty = ctx.get_llvm_type(elt.custom.unwrap());
+        let elem_ty = ctx.get_llvm_type(generator, elt.custom.unwrap());
         let is_range = ctx.unifier.unioned(iter.custom.unwrap(), ctx.primitives.range);
         let list;
         let list_content;
@@ -522,18 +537,16 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator + ?Sized>(
             ctx.builder.build_conditional_branch(is_valid, normal, empty);
             // normal: allocate a list
             ctx.builder.position_at_end(normal);
-            let list_a = allocate_list(ctx, elem_ty, length);
+            let list_a = allocate_list(generator, ctx, elem_ty, length);
             ctx.builder.build_unconditional_branch(list_init);
             ctx.builder.position_at_end(empty);
-            let list_b = allocate_list(ctx, elem_ty, zero);
+            let list_b = allocate_list(generator, ctx, elem_ty, zero);
             ctx.builder.build_unconditional_branch(list_init);
             ctx.builder.position_at_end(list_init);
             let phi = ctx.builder.build_phi(list_a.get_type(), "phi");
             phi.add_incoming(&[(&list_a, normal), (&list_b, empty)]);
             list = phi.as_basic_value().into_pointer_value();
-            list_content = ctx
-                .build_gep_and_load(list, &[zero, int32.const_int(1, false)])
-                .into_pointer_value();
+            list_content = ctx.build_gep_and_load(list, &[zero, zero]).into_pointer_value();
 
             let i = generator.gen_store_target(ctx, target);
             ctx.builder.build_store(i, ctx.builder.build_int_sub(start, step, "start_init"));
@@ -566,35 +579,36 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator + ?Sized>(
             ctx.builder.position_at_end(body_bb);
         } else {
             let length = ctx
-                .build_gep_and_load(iter_val.into_pointer_value(), &[zero, zero])
+                .build_gep_and_load(
+                    iter_val.into_pointer_value(),
+                    &[zero, int32.const_int(1, false)],
+                )
                 .into_int_value();
-            list = allocate_list(ctx, elem_ty, length);
-            list_content = ctx
-                .build_gep_and_load(list, &[zero, int32.const_int(1, false)])
-                .into_pointer_value();
-            let counter = generator.gen_var_alloc(ctx, ctx.primitives.int32);
+            list = allocate_list(generator, ctx, elem_ty, length);
+            list_content = ctx.build_gep_and_load(list, &[zero, zero]).into_pointer_value();
+            let counter = generator.gen_var_alloc(ctx, size_t.into());
             // counter = -1
             ctx.builder.build_store(counter, ctx.ctx.i32_type().const_int(u64::max_value(), true));
             ctx.builder.build_unconditional_branch(test_bb);
             ctx.builder.position_at_end(test_bb);
             let tmp = ctx.builder.build_load(counter, "i").into_int_value();
-            let tmp = ctx.builder.build_int_add(tmp, int32.const_int(1, false), "inc");
+            let tmp = ctx.builder.build_int_add(tmp, size_t.const_int(1, false), "inc");
             ctx.builder.build_store(counter, tmp);
             let cmp = ctx.builder.build_int_compare(inkwell::IntPredicate::SLT, tmp, length, "cmp");
             ctx.builder.build_conditional_branch(cmp, body_bb, cont_bb);
             ctx.builder.position_at_end(body_bb);
             let arr_ptr = ctx
-                .build_gep_and_load(
-                    iter_val.into_pointer_value(),
-                    &[zero, int32.const_int(1, false)],
-                )
+                .build_gep_and_load(iter_val.into_pointer_value(), &[zero, zero])
                 .into_pointer_value();
             let val = ctx.build_gep_and_load(arr_ptr, &[tmp]);
             generator.gen_assign(ctx, target, val.into());
         }
         for cond in ifs.iter() {
-            let result =
-                generator.gen_expr(ctx, cond).unwrap().to_basic_value_enum(ctx).into_int_value();
+            let result = generator
+                .gen_expr(ctx, cond)
+                .unwrap()
+                .to_basic_value_enum(ctx, generator)
+                .into_int_value();
             let succ = ctx.ctx.append_basic_block(current, "then");
             ctx.builder.build_conditional_branch(result, succ, test_bb);
             ctx.builder.position_at_end(succ);
@@ -602,13 +616,14 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator + ?Sized>(
         let elem = generator.gen_expr(ctx, elt).unwrap();
         let i = ctx.builder.build_load(index, "i").into_int_value();
         let elem_ptr = unsafe { ctx.builder.build_gep(list_content, &[i], "elem_ptr") };
-        let val = elem.to_basic_value_enum(ctx);
+        let val = elem.to_basic_value_enum(ctx, generator);
         ctx.builder.build_store(elem_ptr, val);
         ctx.builder
-            .build_store(index, ctx.builder.build_int_add(i, int32.const_int(1, false), "inc"));
+            .build_store(index, ctx.builder.build_int_add(i, size_t.const_int(1, false), "inc"));
         ctx.builder.build_unconditional_branch(test_bb);
         ctx.builder.position_at_end(cont_bb);
-        let len_ptr = unsafe { ctx.builder.build_gep(list, &[zero, zero], "length") };
+        let len_ptr =
+            unsafe { ctx.builder.build_gep(list, &[zero, int32.const_int(1, false)], "length") };
         ctx.builder.build_store(len_ptr, ctx.builder.build_load(index, "index"));
         list.into()
     } else {
@@ -616,7 +631,7 @@ pub fn gen_comprehension<'ctx, 'a, G: CodeGenerator + ?Sized>(
     }
 }
 
-pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
+pub fn gen_expr<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
     expr: &Expr<Option<Type>>,
@@ -641,14 +656,12 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
             // we should use memcpy for that instead of generating thousands of stores
             let elements = elts
                 .iter()
-                .map(|x| generator.gen_expr(ctx, x).unwrap().to_basic_value_enum(ctx))
+                .map(|x| generator.gen_expr(ctx, x).unwrap().to_basic_value_enum(ctx, generator))
                 .collect_vec();
             let ty = if elements.is_empty() { int32.into() } else { elements[0].get_type() };
-            let length = int32.const_int(elements.len() as u64, false);
-            let arr_str_ptr = allocate_list(ctx, ty, length);
-            let arr_ptr = ctx
-                .build_gep_and_load(arr_str_ptr, &[zero, int32.const_int(1, false)])
-                .into_pointer_value();
+            let length = generator.get_size_type(ctx.ctx).const_int(elements.len() as u64, false);
+            let arr_str_ptr = allocate_list(generator, ctx, ty, length);
+            let arr_ptr = ctx.build_gep_and_load(arr_str_ptr, &[zero, zero]).into_pointer_value();
             unsafe {
                 for (i, v) in elements.iter().enumerate() {
                     let elem_ptr = ctx.builder.build_gep(
@@ -664,7 +677,7 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
         ExprKind::Tuple { elts, .. } => {
             let element_val = elts
                 .iter()
-                .map(|x| generator.gen_expr(ctx, x).unwrap().to_basic_value_enum(ctx))
+                .map(|x| generator.gen_expr(ctx, x).unwrap().to_basic_value_enum(ctx, generator))
                 .collect_vec();
             let element_ty = element_val.iter().map(BasicValueEnum::get_type).collect_vec();
             let tuple_ty = ctx.ctx.struct_type(&element_ty, false);
@@ -685,7 +698,7 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
             // note that we would handle class methods directly in calls
             match generator.gen_expr(ctx, value).unwrap() {
                 ValueEnum::Static(v) => v.get_field(*attr, ctx).unwrap_or_else(|| {
-                    let v = v.to_basic_value_enum(ctx);
+                    let v = v.to_basic_value_enum(ctx, generator);
                     let index = ctx.get_attr_index(value.custom.unwrap(), *attr);
                     ValueEnum::Dynamic(ctx.build_gep_and_load(
                         v.into_pointer_value(),
@@ -706,7 +719,7 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
             let left = generator
                 .gen_expr(ctx, &values[0])
                 .unwrap()
-                .to_basic_value_enum(ctx)
+                .to_basic_value_enum(ctx, generator)
                 .into_int_value();
             let current = ctx.builder.get_insert_block().unwrap().get_parent().unwrap();
             let a_bb = ctx.ctx.append_basic_block(current, "a");
@@ -722,7 +735,7 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
                     let b = generator
                         .gen_expr(ctx, &values[1])
                         .unwrap()
-                        .to_basic_value_enum(ctx)
+                        .to_basic_value_enum(ctx, generator)
                         .into_int_value();
                     ctx.builder.build_unconditional_branch(cont_bb);
                     (a, b)
@@ -732,7 +745,7 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
                     let a = generator
                         .gen_expr(ctx, &values[1])
                         .unwrap()
-                        .to_basic_value_enum(ctx)
+                        .to_basic_value_enum(ctx, generator)
                         .into_int_value();
                     ctx.builder.build_unconditional_branch(cont_bb);
                     ctx.builder.position_at_end(b_bb);
@@ -749,8 +762,8 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
         ExprKind::BinOp { op, left, right } => {
             let ty1 = ctx.unifier.get_representative(left.custom.unwrap());
             let ty2 = ctx.unifier.get_representative(right.custom.unwrap());
-            let left = generator.gen_expr(ctx, left).unwrap().to_basic_value_enum(ctx);
-            let right = generator.gen_expr(ctx, right).unwrap().to_basic_value_enum(ctx);
+            let left = generator.gen_expr(ctx, left).unwrap().to_basic_value_enum(ctx, generator);
+            let right = generator.gen_expr(ctx, right).unwrap().to_basic_value_enum(ctx, generator);
 
             // we can directly compare the types, because we've got their representatives
             // which would be unchanged until further unification, which we would never do
@@ -766,7 +779,7 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
         }
         ExprKind::UnaryOp { op, operand } => {
             let ty = ctx.unifier.get_representative(operand.custom.unwrap());
-            let val = generator.gen_expr(ctx, operand).unwrap().to_basic_value_enum(ctx);
+            let val = generator.gen_expr(ctx, operand).unwrap().to_basic_value_enum(ctx, generator);
             if ty == ctx.primitives.bool {
                 let val = val.into_int_value();
                 match op {
@@ -823,8 +836,14 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
                                 BasicValueEnum::IntValue(lhs),
                                 BasicValueEnum::IntValue(rhs),
                             ) = (
-                                generator.gen_expr(ctx, lhs).unwrap().to_basic_value_enum(ctx),
-                                generator.gen_expr(ctx, rhs).unwrap().to_basic_value_enum(ctx),
+                                generator
+                                    .gen_expr(ctx, lhs)
+                                    .unwrap()
+                                    .to_basic_value_enum(ctx, generator),
+                                generator
+                                    .gen_expr(ctx, rhs)
+                                    .unwrap()
+                                    .to_basic_value_enum(ctx, generator),
                             ) {
                                 (lhs, rhs)
                             } else {
@@ -845,8 +864,14 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
                                 BasicValueEnum::FloatValue(lhs),
                                 BasicValueEnum::FloatValue(rhs),
                             ) = (
-                                generator.gen_expr(ctx, lhs).unwrap().to_basic_value_enum(ctx),
-                                generator.gen_expr(ctx, rhs).unwrap().to_basic_value_enum(ctx),
+                                generator
+                                    .gen_expr(ctx, lhs)
+                                    .unwrap()
+                                    .to_basic_value_enum(ctx, generator),
+                                generator
+                                    .gen_expr(ctx, rhs)
+                                    .unwrap()
+                                    .to_basic_value_enum(ctx, generator),
                             ) {
                                 (lhs, rhs)
                             } else {
@@ -871,18 +896,21 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
                 .into() // as there should be at least 1 element, it should never be none
         }
         ExprKind::IfExp { test, body, orelse } => {
-            let test =
-                generator.gen_expr(ctx, test).unwrap().to_basic_value_enum(ctx).into_int_value();
+            let test = generator
+                .gen_expr(ctx, test)
+                .unwrap()
+                .to_basic_value_enum(ctx, generator)
+                .into_int_value();
             let current = ctx.builder.get_insert_block().unwrap().get_parent().unwrap();
             let then_bb = ctx.ctx.append_basic_block(current, "then");
             let else_bb = ctx.ctx.append_basic_block(current, "else");
             let cont_bb = ctx.ctx.append_basic_block(current, "cont");
             ctx.builder.build_conditional_branch(test, then_bb, else_bb);
             ctx.builder.position_at_end(then_bb);
-            let a = generator.gen_expr(ctx, body).unwrap().to_basic_value_enum(ctx);
+            let a = generator.gen_expr(ctx, body).unwrap().to_basic_value_enum(ctx, generator);
             ctx.builder.build_unconditional_branch(cont_bb);
             ctx.builder.position_at_end(else_bb);
-            let b = generator.gen_expr(ctx, orelse).unwrap().to_basic_value_enum(ctx);
+            let b = generator.gen_expr(ctx, orelse).unwrap().to_basic_value_enum(ctx, generator);
             ctx.builder.build_unconditional_branch(cont_bb);
             ctx.builder.position_at_end(cont_bb);
             let phi = ctx.builder.build_phi(a.get_type(), "ifexpr");
@@ -964,27 +992,27 @@ pub fn gen_expr<'ctx, 'a, G: CodeGenerator + ?Sized>(
                     let v = generator
                         .gen_expr(ctx, value)
                         .unwrap()
-                        .to_basic_value_enum(ctx)
+                        .to_basic_value_enum(ctx, generator)
                         .into_pointer_value();
                     let index = generator
                         .gen_expr(ctx, slice)
                         .unwrap()
-                        .to_basic_value_enum(ctx)
+                        .to_basic_value_enum(ctx, generator)
                         .into_int_value();
-                    let arr_ptr =
-                        ctx.build_gep_and_load(v, &[int32.const_zero(), int32.const_int(1, false)]);
+                    let zero = int32.const_zero();
+                    let arr_ptr = ctx.build_gep_and_load(v, &[zero, zero]);
                     ctx.build_gep_and_load(arr_ptr.into_pointer_value(), &[index])
                 }
             } else {
                 let v = generator
                     .gen_expr(ctx, value)
                     .unwrap()
-                    .to_basic_value_enum(ctx)
+                    .to_basic_value_enum(ctx, generator)
                     .into_pointer_value();
                 let index = generator
                     .gen_expr(ctx, slice)
                     .unwrap()
-                    .to_basic_value_enum(ctx)
+                    .to_basic_value_enum(ctx, generator)
                     .into_int_value();
                 ctx.build_gep_and_load(v, &[int32.const_zero(), index])
             }
diff --git a/nac3core/src/codegen/generator.rs b/nac3core/src/codegen/generator.rs
index cf66967e3..6d897b970 100644
--- a/nac3core/src/codegen/generator.rs
+++ b/nac3core/src/codegen/generator.rs
@@ -4,13 +4,19 @@ use crate::{
     toplevel::{DefinitionId, TopLevelDef},
     typecheck::typedef::{FunSignature, Type},
 };
-use inkwell::values::{BasicValueEnum, PointerValue};
+use inkwell::{
+    context::Context,
+    types::{BasicTypeEnum, IntType},
+    values::{BasicValueEnum, PointerValue},
+};
 use nac3parser::ast::{Expr, Stmt, StrRef};
 
 pub trait CodeGenerator {
     /// Return the module name for the code generator.
     fn get_name(&self) -> &str;
 
+    fn get_size_type<'ctx>(&self, ctx: &'ctx Context) -> IntType<'ctx>;
+
     /// Generate function call and returns the function return value.
     /// - obj: Optional object for method call.
     /// - fun: Function signature and definition ID.
@@ -22,7 +28,10 @@ pub trait CodeGenerator {
         obj: Option<(Type, ValueEnum<'ctx>)>,
         fun: (&FunSignature, DefinitionId),
         params: Vec<(Option<StrRef>, ValueEnum<'ctx>)>,
-    ) -> Option<BasicValueEnum<'ctx>> {
+    ) -> Option<BasicValueEnum<'ctx>>
+    where
+        Self: Sized,
+    {
         gen_call(self, ctx, obj, fun, params)
     }
 
@@ -36,7 +45,10 @@ pub trait CodeGenerator {
         signature: &FunSignature,
         def: &TopLevelDef,
         params: Vec<(Option<StrRef>, ValueEnum<'ctx>)>,
-    ) -> BasicValueEnum<'ctx> {
+    ) -> BasicValueEnum<'ctx>
+    where
+        Self: Sized,
+    {
         gen_constructor(self, ctx, signature, def, params)
     }
 
@@ -62,7 +74,10 @@ pub trait CodeGenerator {
         &mut self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
         expr: &Expr<Option<Type>>,
-    ) -> Option<ValueEnum<'ctx>> {
+    ) -> Option<ValueEnum<'ctx>>
+    where
+        Self: Sized,
+    {
         gen_expr(self, ctx, expr)
     }
 
@@ -71,7 +86,7 @@ pub trait CodeGenerator {
     fn gen_var_alloc<'ctx, 'a>(
         &mut self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
-        ty: Type,
+        ty: BasicTypeEnum<'ctx>,
     ) -> PointerValue<'ctx> {
         gen_var(ctx, ty)
     }
@@ -81,7 +96,10 @@ pub trait CodeGenerator {
         &mut self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
         pattern: &Expr<Option<Type>>,
-    ) -> PointerValue<'ctx> {
+    ) -> PointerValue<'ctx>
+    where
+        Self: Sized,
+    {
         gen_store_target(self, ctx, pattern)
     }
 
@@ -91,7 +109,9 @@ pub trait CodeGenerator {
         ctx: &mut CodeGenContext<'ctx, 'a>,
         target: &Expr<Option<Type>>,
         value: ValueEnum<'ctx>,
-    ) {
+    ) where
+        Self: Sized,
+    {
         gen_assign(self, ctx, target, value)
     }
 
@@ -101,7 +121,10 @@ pub trait CodeGenerator {
         &mut self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
         stmt: &Stmt<Option<Type>>,
-    ) -> bool {
+    ) -> bool
+    where
+        Self: Sized,
+    {
         gen_while(self, ctx, stmt);
         false
     }
@@ -112,7 +135,10 @@ pub trait CodeGenerator {
         &mut self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
         stmt: &Stmt<Option<Type>>,
-    ) -> bool {
+    ) -> bool
+    where
+        Self: Sized,
+    {
         gen_for(self, ctx, stmt);
         false
     }
@@ -123,7 +149,10 @@ pub trait CodeGenerator {
         &mut self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
         stmt: &Stmt<Option<Type>>,
-    ) -> bool {
+    ) -> bool
+    where
+        Self: Sized,
+    {
         gen_if(self, ctx, stmt)
     }
 
@@ -131,7 +160,10 @@ pub trait CodeGenerator {
         &mut self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
         stmt: &Stmt<Option<Type>>,
-    ) -> bool {
+    ) -> bool
+    where
+        Self: Sized,
+    {
         gen_with(self, ctx, stmt)
     }
 
@@ -141,18 +173,23 @@ pub trait CodeGenerator {
         &mut self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
         stmt: &Stmt<Option<Type>>,
-    ) -> bool {
+    ) -> bool
+    where
+        Self: Sized,
+    {
         gen_stmt(self, ctx, stmt)
     }
 }
 
 pub struct DefaultCodeGenerator {
     name: String,
+    size_t: u32,
 }
 
 impl DefaultCodeGenerator {
-    pub fn new(name: String) -> DefaultCodeGenerator {
-        DefaultCodeGenerator { name }
+    pub fn new(name: String, size_t: u32) -> DefaultCodeGenerator {
+        assert!(size_t == 32 || size_t == 64);
+        DefaultCodeGenerator { name, size_t }
     }
 }
 
@@ -160,4 +197,14 @@ impl CodeGenerator for DefaultCodeGenerator {
     fn get_name(&self) -> &str {
         &self.name
     }
+
+    fn get_size_type<'ctx>(&self, ctx: &'ctx Context) -> IntType<'ctx> {
+        // it should be unsigned, but we don't really need unsigned and this could save us from
+        // having to do a bit cast...
+        if self.size_t == 32 {
+            ctx.i32_type()
+        } else {
+            ctx.i64_type()
+        }
+    }
 }
diff --git a/nac3core/src/codegen/mod.rs b/nac3core/src/codegen/mod.rs
index d8f9ac903..1ff7c3cdb 100644
--- a/nac3core/src/codegen/mod.rs
+++ b/nac3core/src/codegen/mod.rs
@@ -224,6 +224,7 @@ pub struct CodeGenTask {
 
 fn get_llvm_type<'ctx>(
     ctx: &'ctx Context,
+    generator: &mut dyn CodeGenerator,
     unifier: &mut Unifier,
     top_level: &TopLevelContext,
     type_cache: &mut HashMap<Type, BasicTypeEnum<'ctx>>,
@@ -244,7 +245,7 @@ fn get_llvm_type<'ctx>(
                     let fields = fields.borrow();
                     let fields = fields_list
                         .iter()
-                        .map(|f| get_llvm_type(ctx, unifier, top_level, type_cache, fields[&f.0].0))
+                        .map(|f| get_llvm_type(ctx, generator, unifier, top_level, type_cache, fields[&f.0].0))
                         .collect_vec();
                     ctx.struct_type(&fields, false).ptr_type(AddressSpace::Generic).into()
                 } else {
@@ -256,15 +257,15 @@ fn get_llvm_type<'ctx>(
                 // a struct with fields in the order present in the tuple
                 let fields = ty
                     .iter()
-                    .map(|ty| get_llvm_type(ctx, unifier, top_level, type_cache, *ty))
+                    .map(|ty| get_llvm_type(ctx, generator, unifier, top_level, type_cache, *ty))
                     .collect_vec();
                 ctx.struct_type(&fields, false).ptr_type(AddressSpace::Generic).into()
             }
             TList { ty } => {
                 // a struct with an integer and a pointer to an array
-                let element_type = get_llvm_type(ctx, unifier, top_level, type_cache, *ty);
+                let element_type = get_llvm_type(ctx, generator, unifier, top_level, type_cache, *ty);
                 let fields =
-                    [ctx.i32_type().into(), element_type.ptr_type(AddressSpace::Generic).into()];
+                    [element_type.ptr_type(AddressSpace::Generic).into(), generator.get_size_type(ctx).into()];
                 ctx.struct_type(&fields, false).ptr_type(AddressSpace::Generic).into()
             }
             TVirtual { .. } => unimplemented!(),
@@ -273,7 +274,7 @@ fn get_llvm_type<'ctx>(
     })
 }
 
-pub fn gen_func<'ctx, G: CodeGenerator + ?Sized>(
+pub fn gen_func<'ctx, G: CodeGenerator>(
     context: &'ctx Context,
     generator: &mut G,
     registry: &WorkerRegistry,
@@ -351,14 +352,14 @@ pub fn gen_func<'ctx, G: CodeGenerator + ?Sized>(
     let params = args
         .iter()
         .map(|arg| {
-            get_llvm_type(context, &mut unifier, top_level_ctx.as_ref(), &mut type_cache, arg.ty).into()
+            get_llvm_type(context, generator, &mut unifier, top_level_ctx.as_ref(), &mut type_cache, arg.ty).into()
         })
         .collect_vec();
 
     let fn_type = if unifier.unioned(ret, primitives.none) {
         context.void_type().fn_type(&params, false)
     } else {
-        get_llvm_type(context, &mut unifier, top_level_ctx.as_ref(), &mut type_cache, ret)
+        get_llvm_type(context, generator, &mut unifier, top_level_ctx.as_ref(), &mut type_cache, ret)
             .fn_type(&params, false)
     };
 
@@ -382,7 +383,7 @@ pub fn gen_func<'ctx, G: CodeGenerator + ?Sized>(
     for (n, arg) in args.iter().enumerate() {
         let param = fn_val.get_nth_param(n as u32).unwrap();
         let alloca = builder.build_alloca(
-            get_llvm_type(context, &mut unifier, top_level_ctx.as_ref(), &mut type_cache, arg.ty),
+            get_llvm_type(context, generator, &mut unifier, top_level_ctx.as_ref(), &mut type_cache, arg.ty),
             &arg.name.to_string(),
         );
         builder.build_store(alloca, param);
diff --git a/nac3core/src/codegen/stmt.rs b/nac3core/src/codegen/stmt.rs
index cbad16d75..9acac3d6a 100644
--- a/nac3core/src/codegen/stmt.rs
+++ b/nac3core/src/codegen/stmt.rs
@@ -1,20 +1,27 @@
-use super::{expr::destructure_range, CodeGenContext, CodeGenerator, super::symbol_resolver::ValueEnum};
+use super::{
+    super::symbol_resolver::ValueEnum, expr::destructure_range, CodeGenContext, CodeGenerator,
+};
 use crate::typecheck::typedef::Type;
-use inkwell::values::{BasicValue, BasicValueEnum, PointerValue};
+use inkwell::{
+    types::BasicTypeEnum,
+    values::{BasicValue, BasicValueEnum, PointerValue},
+};
 use nac3parser::ast::{Expr, ExprKind, Stmt, StmtKind};
 
-pub fn gen_var<'ctx, 'a>(ctx: &mut CodeGenContext<'ctx, 'a>, ty: Type) -> PointerValue<'ctx> {
+pub fn gen_var<'ctx, 'a>(
+    ctx: &mut CodeGenContext<'ctx, 'a>,
+    ty: BasicTypeEnum<'ctx>,
+) -> PointerValue<'ctx> {
     // put the alloca in init block
     let current = ctx.builder.get_insert_block().unwrap();
     // position before the last branching instruction...
     ctx.builder.position_before(&ctx.init_bb.get_last_instruction().unwrap());
-    let ty = ctx.get_llvm_type(ty);
     let ptr = ctx.builder.build_alloca(ty, "tmp");
     ctx.builder.position_at_end(current);
     ptr
 }
 
-pub fn gen_store_target<'ctx, 'a, G: CodeGenerator + ?Sized>(
+pub fn gen_store_target<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
     pattern: &Expr<Option<Type>>,
@@ -23,13 +30,14 @@ pub fn gen_store_target<'ctx, 'a, G: CodeGenerator + ?Sized>(
     // and we flatten nested tuples
     match &pattern.node {
         ExprKind::Name { id, .. } => ctx.var_assignment.get(id).map(|v| v.0).unwrap_or_else(|| {
-            let ptr = generator.gen_var_alloc(ctx, pattern.custom.unwrap());
+            let ptr_ty = ctx.get_llvm_type(generator, pattern.custom.unwrap());
+            let ptr = generator.gen_var_alloc(ctx, ptr_ty);
             ctx.var_assignment.insert(*id, (ptr, None, 0));
             ptr
         }),
         ExprKind::Attribute { value, attr, .. } => {
             let index = ctx.get_attr_index(value.custom.unwrap(), *attr);
-            let val = generator.gen_expr(ctx, value).unwrap().to_basic_value_enum(ctx);
+            let val = generator.gen_expr(ctx, value).unwrap().to_basic_value_enum(ctx, generator);
             let ptr = if let BasicValueEnum::PointerValue(v) = val {
                 v
             } else {
@@ -51,10 +59,13 @@ pub fn gen_store_target<'ctx, 'a, G: CodeGenerator + ?Sized>(
             let v = generator
                 .gen_expr(ctx, value)
                 .unwrap()
-                .to_basic_value_enum(ctx)
+                .to_basic_value_enum(ctx, generator)
                 .into_pointer_value();
-            let index =
-                generator.gen_expr(ctx, slice).unwrap().to_basic_value_enum(ctx).into_int_value();
+            let index = generator
+                .gen_expr(ctx, slice)
+                .unwrap()
+                .to_basic_value_enum(ctx, generator)
+                .into_int_value();
             unsafe {
                 let arr_ptr = ctx
                     .build_gep_and_load(v, &[i32_type.const_zero(), i32_type.const_int(1, false)])
@@ -66,14 +77,14 @@ pub fn gen_store_target<'ctx, 'a, G: CodeGenerator + ?Sized>(
     }
 }
 
-pub fn gen_assign<'ctx, 'a, G: CodeGenerator + ?Sized>(
+pub fn gen_assign<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
     target: &Expr<Option<Type>>,
     value: ValueEnum<'ctx>,
 ) {
     if let ExprKind::Tuple { elts, .. } = &target.node {
-        if let BasicValueEnum::PointerValue(ptr) = value.to_basic_value_enum(ctx) {
+        if let BasicValueEnum::PointerValue(ptr) = value.to_basic_value_enum(ctx, generator) {
             let i32_type = ctx.ctx.i32_type();
             for (i, elt) in elts.iter().enumerate() {
                 let v = ctx.build_gep_and_load(
@@ -94,12 +105,12 @@ pub fn gen_assign<'ctx, 'a, G: CodeGenerator + ?Sized>(
                 *static_value = Some(s.clone());
             }
         }
-        let val = value.to_basic_value_enum(ctx);
+        let val = value.to_basic_value_enum(ctx, generator);
         ctx.builder.build_store(ptr, val);
     }
 }
 
-pub fn gen_for<'ctx, 'a, G: CodeGenerator + ?Sized>(
+pub fn gen_for<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
     stmt: &Stmt<Option<Type>>,
@@ -110,6 +121,7 @@ pub fn gen_for<'ctx, 'a, G: CodeGenerator + ?Sized>(
         let var_assignment = ctx.var_assignment.clone();
 
         let int32 = ctx.ctx.i32_type();
+        let size_t = generator.get_size_type(ctx.ctx);
         let zero = int32.const_zero();
         let current = ctx.builder.get_insert_block().unwrap().get_parent().unwrap();
         let test_bb = ctx.ctx.append_basic_block(current, "test");
@@ -121,7 +133,7 @@ pub fn gen_for<'ctx, 'a, G: CodeGenerator + ?Sized>(
         // store loop bb information and restore it later
         let loop_bb = ctx.loop_bb.replace((test_bb, cont_bb));
 
-        let iter_val = generator.gen_expr(ctx, iter).unwrap().to_basic_value_enum(ctx);
+        let iter_val = generator.gen_expr(ctx, iter).unwrap().to_basic_value_enum(ctx, generator);
         if ctx.unifier.unioned(iter.custom.unwrap(), ctx.primitives.range) {
             // setup
             let iter_val = iter_val.into_pointer_value();
@@ -156,25 +168,26 @@ pub fn gen_for<'ctx, 'a, G: CodeGenerator + ?Sized>(
             );
             ctx.builder.position_at_end(body_bb);
         } else {
-            let counter = generator.gen_var_alloc(ctx, ctx.primitives.int32);
+            println!("{:?}", iter_val);
+            let counter = generator.gen_var_alloc(ctx, size_t.into());
             // counter = -1
-            ctx.builder.build_store(counter, ctx.ctx.i32_type().const_int(u64::max_value(), true));
+            ctx.builder.build_store(counter, size_t.const_int(u64::max_value(), true));
             let len = ctx
-                .build_gep_and_load(iter_val.into_pointer_value(), &[zero, zero])
+                .build_gep_and_load(
+                    iter_val.into_pointer_value(),
+                    &[zero, int32.const_int(1, false)],
+                )
                 .into_int_value();
             ctx.builder.build_unconditional_branch(test_bb);
             ctx.builder.position_at_end(test_bb);
             let tmp = ctx.builder.build_load(counter, "i").into_int_value();
-            let tmp = ctx.builder.build_int_add(tmp, int32.const_int(1, false), "inc");
+            let tmp = ctx.builder.build_int_add(tmp, size_t.const_int(1, false), "inc");
             ctx.builder.build_store(counter, tmp);
             let cmp = ctx.builder.build_int_compare(inkwell::IntPredicate::SLT, tmp, len, "cmp");
             ctx.builder.build_conditional_branch(cmp, body_bb, orelse_bb);
             ctx.builder.position_at_end(body_bb);
             let arr_ptr = ctx
-                .build_gep_and_load(
-                    iter_val.into_pointer_value(),
-                    &[zero, int32.const_int(1, false)],
-                )
+                .build_gep_and_load(iter_val.into_pointer_value(), &[zero, zero])
                 .into_pointer_value();
             let val = ctx.build_gep_and_load(arr_ptr, &[tmp]);
             generator.gen_assign(ctx, target, val.into());
@@ -210,7 +223,7 @@ pub fn gen_for<'ctx, 'a, G: CodeGenerator + ?Sized>(
     }
 }
 
-pub fn gen_while<'ctx, 'a, G: CodeGenerator + ?Sized>(
+pub fn gen_while<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
     stmt: &Stmt<Option<Type>>,
@@ -231,7 +244,7 @@ pub fn gen_while<'ctx, 'a, G: CodeGenerator + ?Sized>(
         let loop_bb = ctx.loop_bb.replace((test_bb, cont_bb));
         ctx.builder.build_unconditional_branch(test_bb);
         ctx.builder.position_at_end(test_bb);
-        let test = generator.gen_expr(ctx, test).unwrap().to_basic_value_enum(ctx);
+        let test = generator.gen_expr(ctx, test).unwrap().to_basic_value_enum(ctx, generator);
         if let BasicValueEnum::IntValue(test) = test {
             ctx.builder.build_conditional_branch(test, body_bb, orelse_bb);
         } else {
@@ -268,7 +281,7 @@ pub fn gen_while<'ctx, 'a, G: CodeGenerator + ?Sized>(
     }
 }
 
-pub fn gen_if<'ctx, 'a, G: CodeGenerator + ?Sized>(
+pub fn gen_if<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
     stmt: &Stmt<Option<Type>>,
@@ -291,7 +304,7 @@ pub fn gen_if<'ctx, 'a, G: CodeGenerator + ?Sized>(
         };
         ctx.builder.build_unconditional_branch(test_bb);
         ctx.builder.position_at_end(test_bb);
-        let test = generator.gen_expr(ctx, test).unwrap().to_basic_value_enum(ctx);
+        let test = generator.gen_expr(ctx, test).unwrap().to_basic_value_enum(ctx, generator);
         if let BasicValueEnum::IntValue(test) = test {
             ctx.builder.build_conditional_branch(test, body_bb, orelse_bb);
         } else {
@@ -353,7 +366,7 @@ pub fn gen_if<'ctx, 'a, G: CodeGenerator + ?Sized>(
     }
 }
 
-pub fn gen_with<'ctx, 'a, G: CodeGenerator + ?Sized>(
+pub fn gen_with<'ctx, 'a, G: CodeGenerator>(
     _: &mut G,
     _: &mut CodeGenContext<'ctx, 'a>,
     _: &Stmt<Option<Type>>,
@@ -362,7 +375,7 @@ pub fn gen_with<'ctx, 'a, G: CodeGenerator + ?Sized>(
     unimplemented!()
 }
 
-pub fn gen_stmt<'ctx, 'a, G: CodeGenerator + ?Sized>(
+pub fn gen_stmt<'ctx, 'a, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,
     stmt: &Stmt<Option<Type>>,
@@ -375,7 +388,7 @@ pub fn gen_stmt<'ctx, 'a, G: CodeGenerator + ?Sized>(
         StmtKind::Return { value, .. } => {
             let value = value
                 .as_ref()
-                .map(|v| generator.gen_expr(ctx, v).unwrap().to_basic_value_enum(ctx));
+                .map(|v| generator.gen_expr(ctx, v).unwrap().to_basic_value_enum(ctx, generator));
             let value = value.as_ref().map(|v| v as &dyn BasicValue);
             ctx.builder.build_return(value);
             return true;
@@ -408,8 +421,10 @@ pub fn gen_stmt<'ctx, 'a, G: CodeGenerator + ?Sized>(
             let value = {
                 let ty1 = ctx.unifier.get_representative(target.custom.unwrap());
                 let ty2 = ctx.unifier.get_representative(value.custom.unwrap());
-                let left = generator.gen_expr(ctx, target).unwrap().to_basic_value_enum(ctx);
-                let right = generator.gen_expr(ctx, value).unwrap().to_basic_value_enum(ctx);
+                let left =
+                    generator.gen_expr(ctx, target).unwrap().to_basic_value_enum(ctx, generator);
+                let right =
+                    generator.gen_expr(ctx, value).unwrap().to_basic_value_enum(ctx, generator);
 
                 // we can directly compare the types, because we've got their representatives
                 // which would be unchanged until further unification, which we would never do
diff --git a/nac3core/src/codegen/test.rs b/nac3core/src/codegen/test.rs
index 2bbc75ed8..34fcf3f48 100644
--- a/nac3core/src/codegen/test.rs
+++ b/nac3core/src/codegen/test.rs
@@ -39,7 +39,7 @@ impl SymbolResolver for Resolver {
     fn get_default_param_value(&self, _: &nac3parser::ast::Expr) -> Option<crate::symbol_resolver::SymbolValue> {
         unimplemented!()
     }
-    
+
     fn get_symbol_type(
         &self,
         _: &mut Unifier,
@@ -88,7 +88,7 @@ fn test_primitives() {
         class_names: Default::default(),
     }) as Arc<dyn SymbolResolver + Send + Sync>;
 
-    let threads = vec![DefaultCodeGenerator::new("test".into()).into()];
+    let threads = vec![DefaultCodeGenerator::new("test".into(), 32).into()];
     let signature = FunSignature {
         args: vec![
             FuncArg { name: "a".into(), ty: primitives.int32, default_value: None },
@@ -245,7 +245,7 @@ fn test_simple_call() {
         unreachable!()
     }
 
-    let threads = vec![DefaultCodeGenerator::new("test".into()).into()];
+    let threads = vec![DefaultCodeGenerator::new("test".into(), 32).into()];
     let mut function_data = FunctionData {
         resolver: resolver.clone(),
         bound_variables: Vec::new(),
diff --git a/nac3core/src/symbol_resolver.rs b/nac3core/src/symbol_resolver.rs
index 742bfafac..c5dbe54ff 100644
--- a/nac3core/src/symbol_resolver.rs
+++ b/nac3core/src/symbol_resolver.rs
@@ -2,10 +2,10 @@ use std::collections::HashMap;
 use std::fmt::Debug;
 use std::{cell::RefCell, sync::Arc};
 
-use crate::typecheck::{
+use crate::{codegen::CodeGenerator, typecheck::{
     type_inferencer::PrimitiveStore,
     typedef::{Type, Unifier},
-};
+}};
 use crate::{
     codegen::CodeGenContext,
     toplevel::{DefinitionId, TopLevelDef},
@@ -31,6 +31,7 @@ pub trait StaticValue {
     fn to_basic_value_enum<'ctx, 'a>(
         &self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
+        generator: &mut dyn CodeGenerator
     ) -> BasicValueEnum<'ctx>;
 
     fn get_field<'ctx, 'a>(
@@ -74,9 +75,10 @@ impl<'ctx> ValueEnum<'ctx> {
     pub fn to_basic_value_enum<'a>(
         self,
         ctx: &mut CodeGenContext<'ctx, 'a>,
+        generator: &mut dyn CodeGenerator,
     ) -> BasicValueEnum<'ctx> {
         match self {
-            ValueEnum::Static(v) => v.to_basic_value_enum(ctx),
+            ValueEnum::Static(v) => v.to_basic_value_enum(ctx, generator),
             ValueEnum::Dynamic(v) => v,
         }
     }
diff --git a/nac3standalone/src/main.rs b/nac3standalone/src/main.rs
index d50071290..f3a6b3073 100644
--- a/nac3standalone/src/main.rs
+++ b/nac3standalone/src/main.rs
@@ -295,7 +295,7 @@ fn main() {
         // println!("IR:\n{}", module.print_to_string().to_str().unwrap());
     })));
     let threads = (0..threads)
-        .map(|i| Box::new(DefaultCodeGenerator::new(format!("module{}", i))))
+        .map(|i| Box::new(DefaultCodeGenerator::new(format!("module{}", i), 64)))
         .collect();
     let (registry, handles) = WorkerRegistry::create_workers(threads, top_level, f);
     registry.add_task(task);