2 files changed, 5 insertions, 1 deletions
diff --git a/gc.c b/gc.c
index 9c7114e5a7..b441a0beb2 100644
--- a/gc.c
+++ b/gc.c
@@ -1448,6 +1448,8 @@ os_each_obj(int argc, VALUE *argv, VALUE os)
 static VALUE
 undefine_final(VALUE os, VALUE obj)
 {
+    rb_check_frozen(obj);
+
     rb_gc_impl_undefine_finalizer(rb_gc_get_objspace(), obj);
 
     return obj;
diff --git a/gc/default.c b/gc/default.c
index e5662fc586..65006a2e32 100644
--- a/gc/default.c
+++ b/gc/default.c
@@ -3005,8 +3005,10 @@ void
 rb_gc_impl_undefine_finalizer(void *objspace_ptr, VALUE obj)
 {
     rb_objspace_t *objspace = objspace_ptr;
+
+    GC_ASSERT(!OBJ_FROZEN(obj));
+
     st_data_t data = obj;
-    rb_check_frozen(obj);
     st_delete(finalizer_table, &data, 0);
     FL_UNSET(obj, FL_FINALIZE);
 }