From e596cf6e93dbf121e197cccfec8a69902e00eda3 Mon Sep 17 00:00:00 2001
From: John Hawthorn <john.hawthorn@shopify.com>
Date: Wed, 28 May 2025 10:11:58 -0700
Subject: [PATCH] Make FrozenCore a plain T_CLASS

---
 gc.c | 5 ++++-
 vm.c | 3 ---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/gc.c b/gc.c
index 6c230d7820..9b218934b4 100644
--- a/gc.c
+++ b/gc.c
@@ -1491,7 +1491,10 @@ internal_object_p(VALUE obj)
           case T_ZOMBIE:
             break;
           case T_CLASS:
-            if (!RBASIC(obj)->klass) break;
+            if (obj == rb_mRubyVMFrozenCore)
+                return 1;
+
+            if (!RBASIC_CLASS(obj)) break;
             if (RCLASS_SINGLETON_P(obj)) {
                 return rb_singleton_class_internal_p(obj);
             }
diff --git a/vm.c b/vm.c
index c2f90bd09e..f3e4f1e2ce 100644
--- a/vm.c
+++ b/vm.c
@@ -4011,9 +4011,6 @@ Init_VM(void)
     fcore = rb_class_new(rb_cBasicObject);
     rb_set_class_path(fcore, rb_cRubyVM, "FrozenCore");
     rb_vm_register_global_object(rb_class_path_cached(fcore));
-    RB_FL_UNSET_RAW(fcore, T_MASK);
-    RB_FL_SET_RAW(fcore, T_ICLASS);
-    RCLASSEXT_ICLASS_IS_ORIGIN(RCLASS_EXT_PRIME(fcore)) = true;
     klass = rb_singleton_class(fcore);
     rb_define_method_id(klass, id_core_set_method_alias, m_core_set_method_alias, 3);
     rb_define_method_id(klass, id_core_set_variable_alias, m_core_set_variable_alias, 2);