diff --git a/nac3core/src/toplevel/builtins.rs b/nac3core/src/toplevel/builtins.rs
index 008f24de..e6de64ee 100644
--- a/nac3core/src/toplevel/builtins.rs
+++ b/nac3core/src/toplevel/builtins.rs
@@ -9,16 +9,19 @@ use inkwell::{
     IntPredicate,
 };
 use itertools::Either;
+use ndarray::basic::call_nac3_ndarray_len;
 use strum::IntoEnumIterator;
 
 use crate::{
     codegen::{
         builtin_fns,
-        classes::{ArrayLikeValue, NDArrayValue, ProxyValue, RangeValue, TypedArrayLikeAccessor},
+        classes::{ProxyValue, RangeValue},
         expr::destructure_range,
         irrt::*,
+        model::*,
         numpy::*,
         stmt::exn_constructor,
+        structure::ndarray::NpArray,
     },
     symbol_resolver::SymbolValue,
     toplevel::{helper::PrimDef, numpy::make_ndarray_ty},
@@ -1464,51 +1467,13 @@ impl<'a> BuiltinBuilder<'a> {
                                 }
                             }
                             TypeEnum::TObj { obj_id, .. } if *obj_id == PrimDef::NDArray.id() => {
-                                let llvm_i32 = ctx.ctx.i32_type();
-                                let llvm_usize = generator.get_size_type(ctx.ctx);
+                                let tyctx = generator.type_context(ctx.ctx);
+                                let pndarray_model = PtrModel(StructModel(NpArray));
 
-                                let arg = NDArrayValue::from_ptr_val(
-                                    arg.into_pointer_value(),
-                                    llvm_usize,
-                                    None,
-                                );
-
-                                let ndims = arg.dim_sizes().size(ctx, generator);
-                                ctx.make_assert(
-                                    generator,
-                                    ctx.builder
-                                        .build_int_compare(
-                                            IntPredicate::NE,
-                                            ndims,
-                                            llvm_usize.const_zero(),
-                                            "",
-                                        )
-                                        .unwrap(),
-                                    "0:TypeError",
-                                    &format!("{name}() of unsized object", name = prim.name()),
-                                    [None, None, None],
-                                    ctx.current_loc,
-                                );
-
-                                let len = unsafe {
-                                    arg.dim_sizes().get_typed_unchecked(
-                                        ctx,
-                                        generator,
-                                        &llvm_usize.const_zero(),
-                                        None,
-                                    )
-                                };
-
-                                if len.get_type().get_bit_width() == 32 {
-                                    Some(len.into())
-                                } else {
-                                    Some(
-                                        ctx.builder
-                                            .build_int_truncate(len, llvm_i32, "len")
-                                            .map(Into::into)
-                                            .unwrap(),
-                                    )
-                                }
+                                let ndarray =
+                                    pndarray_model.check_value(tyctx, ctx.ctx, arg).unwrap();
+                                let len = call_nac3_ndarray_len(generator, ctx, ndarray);
+                                Some(len.value.as_basic_value_enum())
                             }
                             _ => unreachable!(),
                         }