diff --git a/vm/src/obj/objfloat.rs b/vm/src/obj/objfloat.rs
index 2adc29113..8d0dcc1ed 100644
--- a/vm/src/obj/objfloat.rs
+++ b/vm/src/obj/objfloat.rs
@@ -4,14 +4,14 @@ use num_rational::Ratio;
 use num_traits::{float::Float, pow, sign::Signed, ToPrimitive, Zero};
 
 use super::objbytes;
-use super::objint;
+use super::objint::{self, PyIntRef};
 use super::objstr::{self, PyStringRef};
 use super::objtype::{self, PyClassRef};
-use crate::function::OptionalArg;
+use crate::function::{OptionalArg, OptionalOption};
 use crate::pyhash;
 use crate::pyobject::{
-    IdProtocol, IntoPyObject, PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue,
-    TryFromObject, TypeProtocol,
+    IntoPyObject, PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue, TryFromObject,
+    TypeProtocol,
 };
 use crate::vm::VirtualMachine;
 
@@ -458,26 +458,10 @@ impl PyFloat {
     }
 
     #[pymethod(name = "__round__")]
-    fn round(&self, ndigits: OptionalArg<PyObjectRef>, vm: &VirtualMachine) -> PyResult {
-        let ndigits = match ndigits {
-            OptionalArg::Missing => None,
-            OptionalArg::Present(ref value) => {
-                if !vm.get_none().is(value) {
-                    if !objtype::isinstance(value, &vm.ctx.int_type()) {
-                        return Err(vm.new_type_error(format!(
-                            "'{}' object cannot be interpreted as an integer",
-                            value.class().name
-                        )));
-                    };
-                    // Only accept int type ndigits
-                    let ndigits = objint::get_value(value);
-                    Some(ndigits)
-                } else {
-                    None
-                }
-            }
-        };
+    fn round(&self, ndigits: OptionalOption<PyIntRef>, vm: &VirtualMachine) -> PyResult {
+        let ndigits = ndigits.flat_option();
         if let Some(ndigits) = ndigits {
+            let ndigits = ndigits.as_bigint();
             if ndigits.is_zero() {
                 let fract = self.value.fract();
                 let value = if (fract.abs() - 0.5).abs() < std::f64::EPSILON {