diff --git a/ChangeLog b/ChangeLog
index d12cc150b6..388d7c7f8c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Dec  5 17:56:36 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* class.c (make_metaclass): fix probable typo.  builtin type flag
+	  cannot be used with FL_TEST.
+
 Sun Dec  5 12:09:27 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* lib/irb/init.rb (IRB.parse_opts): fix typo. [ruby-core:33574]
diff --git a/class.c b/class.c
index 6d64873ff3..76f4ef8622 100644
--- a/class.c
+++ b/class.c
@@ -314,7 +314,7 @@ make_metaclass(VALUE klass)
     }
 
     super = RCLASS_SUPER(klass);
-    while (FL_TEST(super, T_ICLASS)) super = RCLASS_SUPER(super);
+    while (RB_TYPE_P(super, T_ICLASS)) super = RCLASS_SUPER(super);
     RCLASS_SUPER(metaclass) = super ? ENSURE_EIGENCLASS(super) : rb_cClass;
 
     OBJ_INFECT(metaclass, RCLASS_SUPER(metaclass));