diff --git a/object.c b/object.c
index 4d54b73740..28e6125421 100644
--- a/object.c
+++ b/object.c
@@ -337,12 +337,10 @@ rb_obj_copy_ivar(VALUE dest, VALUE obj)
         return;
     }
 
-    shape_id_t dest_shape_id = src_shape_id;
     shape_id_t initial_shape_id = RBASIC_SHAPE_ID(dest);
-
     RUBY_ASSERT(RSHAPE_TYPE_P(initial_shape_id, SHAPE_ROOT));
 
-    dest_shape_id = rb_shape_rebuild(initial_shape_id, src_shape_id);
+    shape_id_t dest_shape_id = rb_shape_rebuild(initial_shape_id, src_shape_id);
     if (UNLIKELY(rb_shape_too_complex_p(dest_shape_id))) {
         st_table *table = rb_st_init_numtable_with_size(src_num_ivs);
         rb_obj_copy_ivs_to_hash_table(obj, table);