diff --git a/ChangeLog b/ChangeLog
index 67467e89a0..21b422b0a4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Feb  5 11:37:47 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* array.c (ary_make_hash): hide a Hash used internally.
+
 Thu Feb  5 11:21:35 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* configure.in (RUBY_LIB_VERSION): added for library version, to
diff --git a/array.c b/array.c
index 13bf3b674e..ddfe3c2b2b 100644
--- a/array.c
+++ b/array.c
@@ -2869,6 +2869,7 @@ ary_make_hash(VALUE ary1, VALUE ary2)
     VALUE hash = rb_hash_new();
     long i;
 
+    RBASIC(hash)->klass = 0;
     for (i=0; i<RARRAY_LEN(ary1); i++) {
 	rb_hash_aset(hash, RARRAY_PTR(ary1)[i], Qtrue);
     }