diff --git a/ChangeLog b/ChangeLog
index 99de2cbd46..d6f0e51b42 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Oct 17 10:40:17 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* class.c (rb_define_{class,module}_id_under): register to be
+	  marked, which probably are defined and used internally.
+
 Sat Oct 16 11:10:55 2010  Masaki Suketa <masaki.suketa@nifty.ne.jp>
 
 	* ext/win32ole/win32ole.c (ole_encoding2cp): set codepage 20936
diff --git a/class.c b/class.c
index 4610f4dfa7..31b407038e 100644
--- a/class.c
+++ b/class.c
@@ -524,6 +524,7 @@ rb_define_class_id_under(VALUE outer, ID id, VALUE super)
     rb_set_class_path_string(klass, outer, rb_id2str(id));
     rb_const_set(outer, id, klass);
     rb_class_inherited(super, klass);
+    rb_gc_register_mark_object(klass);
 
     return klass;
 }
@@ -590,6 +591,7 @@ rb_define_module_id_under(VALUE outer, ID id)
     module = rb_define_module_id(id);
     rb_const_set(outer, id, module);
     rb_set_class_path_string(module, outer, rb_id2str(id));
+    rb_gc_register_mark_object(module);
 
     return module;
 }
diff --git a/test/ruby/test_class.rb b/test/ruby/test_class.rb
index c81f0752d4..3f18294e0f 100644
--- a/test/ruby/test_class.rb
+++ b/test/ruby/test_class.rb
@@ -236,4 +236,8 @@ class TestClass < Test::Unit::TestCase
     copy.send(:include, mod)
     assert_equal("mod#foo", copy.new.foo)
   end
+
+  def test_nested_class_removal
+    assert_normal_exit('File.__send__(:remove_const, :Stat); at_exit{File.stat(".")}; GC.start')
+  end
 end
diff --git a/version.h b/version.h
index b579dcf7c6..a124ed8c9d 100644
--- a/version.h
+++ b/version.h
@@ -1,11 +1,11 @@
 #define RUBY_VERSION "1.9.3"
-#define RUBY_RELEASE_DATE "2010-10-16"
+#define RUBY_RELEASE_DATE "2010-10-17"
 #define RUBY_PATCHLEVEL -1
 #define RUBY_BRANCH_NAME "trunk"
 
 #define RUBY_RELEASE_YEAR 2010
 #define RUBY_RELEASE_MONTH 10
-#define RUBY_RELEASE_DAY 16
+#define RUBY_RELEASE_DAY 17
 
 #include "ruby/version.h"