diff --git a/vm/src/builtins/object.rs b/vm/src/builtins/object.rs
index 127351cba..871a0b935 100644
--- a/vm/src/builtins/object.rs
+++ b/vm/src/builtins/object.rs
@@ -5,7 +5,6 @@ use crate::{
     PyArithmeticValue, PyAttributes, PyClassImpl, PyComparisonValue, PyContext, PyGenericObject,
     PyObject, PyObjectRef, PyResult, PyValue, TypeProtocol, VirtualMachine,
 };
-use num_bigint::BigInt;
 
 /// object()
 /// --
@@ -38,10 +37,8 @@ impl PyBaseObject {
 
         // Ensure that all abstract methods are implemented before instantiating instance.
         if let Some(abs_methods) = cls.get_attr("__abstractmethods__") {
-            if let Some(iter) = vm.get_method(abs_methods, "__len__") {
-                let values = vm.invoke(&iter?, ())?;
-                let unimplemented_abstract_method_count = super::int::get_value(&values);
-                if unimplemented_abstract_method_count > &BigInt::from(0) {
+            if let Some(unimplemented_abstract_method_count) = vm.obj_len_opt(&abs_methods) {
+                if unimplemented_abstract_method_count? > 0 {
                     return Err(
                         vm.new_type_error("You must implement the abstract methods".to_owned())
                     );