diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 3955a523d0..2fc9b96114 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -5493,7 +5493,7 @@ vm_define_method(const rb_execution_context_t *ec, VALUE obj, ID id, VALUE iseqv
 
     rb_add_method_iseq(klass, id, (const rb_iseq_t *)iseqval, cref, visi);
     // Set max_iv_count on klasses based on number of ivar sets that are in the initialize method
-    if (id == rb_intern("initialize") && klass != rb_cObject &&  RB_TYPE_P(klass, T_CLASS) && (rb_get_alloc_func(klass) == rb_class_allocate_instance)) {
+    if (id == idInitialize && klass != rb_cObject &&  RB_TYPE_P(klass, T_CLASS) && (rb_get_alloc_func(klass) == rb_class_allocate_instance)) {
 
         RCLASS_EXT(klass)->max_iv_count = rb_estimate_iv_count(klass, (const rb_iseq_t *)iseqval);
     }