diff --git a/ChangeLog b/ChangeLog
index 2ab7dd5669..453902c6bd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Aug  4 05:43:03 2009  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* thread.c (recursive_push): need to set UNTRUST.  [ruby-dev:38997]
+
 Tue Aug  4 03:56:51 2009  Hidetoshi NAGAI  <nagai@ai.kyutech.ac.jp>
 
 	* ext/tk/lib/tcltklib.c: fix trouble on old-style C function
diff --git a/thread.c b/thread.c
index 3870fc19ab..24b550f75d 100644
--- a/thread.c
+++ b/thread.c
@@ -3354,6 +3354,7 @@ recursive_push(VALUE hash, VALUE obj, VALUE paired_obj)
     sym = ID2SYM(rb_frame_this_func());
     if (NIL_P(hash) || TYPE(hash) != T_HASH) {
 	hash = rb_hash_new();
+	OBJ_UNTRUST(hash);
 	rb_thread_local_aset(rb_thread_current(), recursive_key, hash);
 	list = Qnil;
     }