diff --git a/nac3core/irrt/irrt/range.hpp b/nac3core/irrt/irrt/range.hpp
index 651cc597..c1d8fd26 100644
--- a/nac3core/irrt/irrt/range.hpp
+++ b/nac3core/irrt/irrt/range.hpp
@@ -46,4 +46,9 @@ extern "C"
     {
         return range::len(start, stop, step);
     }
+
+    int64_t __nac3_range_len_i64(int64_t start, int64_t stop, int64_t step)
+    {
+        return range::len(start, stop, step);
+    }
 }
\ No newline at end of file
diff --git a/nac3core/src/codegen/irrt/mod.rs b/nac3core/src/codegen/irrt/mod.rs
index c7fe3e01..5c18cdaf 100644
--- a/nac3core/src/codegen/irrt/mod.rs
+++ b/nac3core/src/codegen/irrt/mod.rs
@@ -609,18 +609,30 @@ pub fn setup_irrt_exceptions<'ctx>(
     }
 }
 
-pub fn call_nac3_range_len_i32<'ctx, G: CodeGenerator + ?Sized>(
+pub fn call_nac3_range_len<'ctx, G: CodeGenerator + ?Sized, N: IntKind<'ctx>>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, '_>,
-    start: Instance<'ctx, Int<Int32>>,
-    stop: Instance<'ctx, Int<Int32>>,
-    step: Instance<'ctx, Int<Int32>>,
-) -> Instance<'ctx, Int<Int32>> {
-    CallFunction::begin(generator, ctx, "__nac3_range_len_i32")
+    int_kind: N,
+    start: IntValue<'ctx>,
+    stop: IntValue<'ctx>,
+    step: IntValue<'ctx>,
+) -> Instance<'ctx, Int<N>> {
+    let start = Int(int_kind).check_value(generator, ctx.ctx, start).unwrap();
+    let stop = Int(int_kind).check_value(generator, ctx.ctx, stop).unwrap();
+    let step = Int(int_kind).check_value(generator, ctx.ctx, step).unwrap();
+
+    let bit_width = int_kind.get_int_type(generator, ctx.ctx).get_bit_width();
+    let func_name = match bit_width {
+        32 => "__nac3_range_len_i32",
+        64 => "__nac3_range_len_i64",
+        _ => panic!("{bit_width}-bits ints not supported"), // We could add more variants when necessary.
+    };
+
+    CallFunction::begin(generator, ctx, func_name)
         .arg(start)
         .arg(stop)
         .arg(step)
-        .returning_auto("range_len")
+        .returning("range_len", Int(int_kind))
 }
 
 pub fn call_nac3_ndarray_util_assert_shape_no_negative<'ctx, G: CodeGenerator + ?Sized>(
diff --git a/nac3core/src/codegen/object/range.rs b/nac3core/src/codegen/object/range.rs
index 5ca84fca..127ad935 100644
--- a/nac3core/src/codegen/object/range.rs
+++ b/nac3core/src/codegen/object/range.rs
@@ -1,6 +1,6 @@
 use inkwell::{values::IntValue, IntPredicate};
 
-use crate::codegen::{irrt::call_nac3_range_len_i32, model::*, CodeGenContext, CodeGenerator};
+use crate::codegen::{irrt::call_nac3_range_len, model::*, CodeGenContext, CodeGenerator};
 
 use super::any::AnyObject;
 
@@ -63,6 +63,45 @@ pub fn assert_range_step_non_zero<'ctx, G: CodeGenerator + ?Sized>(
     );
 }
 
+/// A Rust structure that has [`Range`] utilities and looks like a [`Range`] but
+/// `start`, `stop` and `step` are held by LLVM registers only.
+///
+/// This structure exists because many implementations use [`Range`] utilities but
+/// it might not be good to alloca an actual [`Range`] value on the stack in order
+/// to perform calculations.
+pub struct RustRange<'ctx, N: IntKind<'ctx>> {
+    pub start: Instance<'ctx, Int<N>>,
+    pub stop: Instance<'ctx, Int<N>>,
+    pub step: Instance<'ctx, Int<N>>,
+}
+
+impl<'ctx, N: IntKind<'ctx>> RustRange<'ctx, N> {
+    pub fn assert_step_non_zero<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &mut CodeGenContext<'ctx, '_>,
+    ) {
+        assert_range_step_non_zero(generator, ctx, self.step.value);
+    }
+
+    /// Calculate the `len()` of this range.
+    pub fn len<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &mut CodeGenContext<'ctx, '_>,
+    ) -> Instance<'ctx, Int<N>> {
+        let int_kind = self.start.model.0;
+        call_nac3_range_len(
+            generator,
+            ctx,
+            int_kind,
+            self.start.value,
+            self.stop.value,
+            self.step.value,
+        )
+    }
+}
+
 // TODO: `RangeObject` in the future will have range32, range64
 
 /// A NAC3 Python range object.
@@ -84,14 +123,24 @@ impl<'ctx> RangeObject<'ctx> {
         RangeObject { instance }
     }
 
+    /// Convert into a [`RustRange`].
+    pub fn as_rust_range<G: CodeGenerator + ?Sized>(
+        &self,
+        generator: &mut G,
+        ctx: &mut CodeGenContext<'ctx, '_>,
+    ) -> RustRange<'ctx, Int32> {
+        let (start, stop, step) = self.instance.destructure(generator, ctx);
+        RustRange { start, stop, step }
+    }
+
     /// Get the `len()` of this range.
     pub fn len<G: CodeGenerator + ?Sized>(
         &self,
         generator: &mut G,
         ctx: &mut CodeGenContext<'ctx, '_>,
     ) -> Instance<'ctx, Int<Int32>> {
-        let (start, stop, step) = self.instance.destructure(generator, ctx);
-        assert_range_step_non_zero(generator, ctx, step.value);
-        call_nac3_range_len_i32(generator, ctx, start, stop, step)
+        let range = self.as_rust_range(generator, ctx);
+        range.assert_step_non_zero(generator, ctx);
+        range.len(generator, ctx)
     }
 }