diff --git a/ChangeLog b/ChangeLog
index 544fef4aaa..60564af72d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Oct  4 15:04:43 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* class.c (class_alloc): allocate extra memory after containing
+	  object setup to get rid of rare-but-potential memory leak.
+
 Tue Oct  4 11:44:10 2011  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* gc.c (rb_gc_set_params): ruby_verbose can be Qnil, so use RTEST.
diff --git a/class.c b/class.c
index e6c1f8fd11..b595473333 100644
--- a/class.c
+++ b/class.c
@@ -49,10 +49,9 @@ static ID id_attached;
 static VALUE
 class_alloc(VALUE flags, VALUE klass)
 {
-    rb_classext_t *ext = ALLOC(rb_classext_t);
     NEWOBJ(obj, struct RClass);
     OBJSETUP(obj, klass, flags);
-    obj->ptr = ext;
+    obj->ptr = ALLOC(rb_classext_t);
     RCLASS_IV_TBL(obj) = 0;
     RCLASS_CONST_TBL(obj) = 0;
     RCLASS_M_TBL(obj) = 0;