diff --git a/src/heap.rs b/src/heap.rs
index f8e2b43..f60ab37 100644
--- a/src/heap.rs
+++ b/src/heap.rs
@@ -25,7 +25,7 @@ pub enum ObjectRef{
     BooleanArray(Vec<bool>),
     CharArray(Vec<char>),
     ObjectArray(Vec<Arc<UnsafeCell<ObjectRef>>>),
-    Object(Object),
+    Object(Box<Object>),
 }
 
 
diff --git a/src/vm.rs b/src/vm.rs
index 69d6d42..6f8c2d4 100644
--- a/src/vm.rs
+++ b/src/vm.rs
@@ -348,7 +348,7 @@ impl Vm {
                             {
                                 println!("new {}", new_class);
                                 let class = self.get_class(new_class)?;
-                                let object = Arc::new(UnsafeCell::new(ObjectRef::Object(self.new_instance(class))));
+                                let object = Arc::new(UnsafeCell::new(ObjectRef::Object(Box::new(self.new_instance(class)))));
                                 self.local_stack().push(Value::Ref(Arc::clone(&object)));
                                 self.heap.new_object(object);
                             }