diff --git a/crates/vm/src/builtins/int.rs b/crates/vm/src/builtins/int.rs
index 9b74b66e3a7..cc42d02733a 100644
--- a/crates/vm/src/builtins/int.rs
+++ b/crates/vm/src/builtins/int.rs
@@ -444,7 +444,8 @@ impl PyInt {
 
     #[pymethod]
     fn __sizeof__(&self) -> usize {
-        core::mem::size_of::<Self>() + (((self.value.bits() + 7) & !7) / 8) as usize
+        let digits = self.value.iter_u32_digits().count().max(1);
+        core::mem::size_of::<Self>() + (<Self as crate::class::PyClassDef>::ITEMSIZE * digits)
     }
 
     #[pymethod]
diff --git a/crates/vm/src/builtins/object.rs b/crates/vm/src/builtins/object.rs
index 6f072542547..5d4bfe80fd8 100644
--- a/crates/vm/src/builtins/object.rs
+++ b/crates/vm/src/builtins/object.rs
@@ -1,4 +1,4 @@
-use super::{PyDictRef, PyList, PyStr, PyStrRef, PyType, PyTypeRef};
+use super::{PyDictRef, PyInt, PyList, PyStr, PyStrRef, PyType, PyTypeRef};
 use crate::common::hash::PyHash;
 use crate::types::PyTypeFlags;
 use crate::{
@@ -526,6 +526,13 @@ impl PyBaseObject {
 
     #[pymethod]
     fn __sizeof__(zelf: PyObjectRef) -> usize {
+        if let Some(int) = zelf.downcast_ref::<PyInt>() {
+            let digits = int.as_bigint().iter_u32_digits().count();
+            let basicsize = zelf.class().slots.basicsize;
+            let itemsize = zelf.class().slots.itemsize;
+            return basicsize + itemsize * digits;
+        }
+
         zelf.class().slots.basicsize
     }
 }
diff --git a/extra_tests/snippets/builtin_object.py b/extra_tests/snippets/builtin_object.py
index 64486e1673e..98c78c679fe 100644
--- a/extra_tests/snippets/builtin_object.py
+++ b/extra_tests/snippets/builtin_object.py
@@ -32,3 +32,6 @@ class MyObject:
     0: "ab",
 }
 assert "ab ab" == "{k[0]} {vv}".format(k=d, vv=d[0])
+
+big = 1223456789812391231291231231231212312312312312312312321321321321312312321123123123199129391239219394923912949213021949302194942130123949203912430392402139210492139123012940219394923942395943856228368385
+assert object.__sizeof__(big) >= big.__sizeof__()