diff --git a/ChangeLog b/ChangeLog
index 8be2fa40bb..6929c73e70 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Fri Jun 13 12:55:37 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* enum.c (sort_by_i): use NODE_DOT2 instead of NODE_MEMO to avoid
+	  extra calls to is_pointer_to_heap() in GC.
+
+	* enum.c (enum_zip): ditto.
+
 Fri Jun 13 00:41:58 2008  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* test/ruby/test_thread.rb: add a test.
diff --git a/enum.c b/enum.c
index e4d4ee5969..b704732d91 100644
--- a/enum.c
+++ b/enum.c
@@ -691,7 +691,8 @@ sort_by_i(VALUE i, VALUE ary, int argc, VALUE *argv)
     if (RBASIC(ary)->klass) {
 	rb_raise(rb_eRuntimeError, "sort_by reentered");
     }
-    memo = rb_node_newnode(NODE_MEMO, rb_yield(i), i, 0);
+    /* use NODE_DOT2 as memo(v, v, -) */
+    memo = rb_node_newnode(NODE_DOT2, rb_yield(i), i, 0);
     rb_ary_push(ary, (VALUE)memo);
     return Qnil;
 }
@@ -1574,7 +1575,8 @@ enum_zip(int argc, VALUE *argv, VALUE obj)
     if (!rb_block_given_p()) {
 	result = rb_ary_new();
     }
-    memo = rb_node_newnode(NODE_MEMO, result, rb_ary_new4(argc, argv), 0);
+    /* use NODE_DOT2 as memo(v, v, -) */
+    memo = rb_node_newnode(NODE_DOT2, result, rb_ary_new4(argc, argv), 0);
     rb_block_call(obj, id_each, 0, 0, allary ? zip_ary : zip_i, (VALUE)memo);
 
     return result;
diff --git a/version.h b/version.h
index b04cf2d790..a8aebd55a3 100644
--- a/version.h
+++ b/version.h
@@ -1,7 +1,7 @@
 #define RUBY_VERSION "1.9.0"
-#define RUBY_RELEASE_DATE "2008-06-12"
+#define RUBY_RELEASE_DATE "2008-06-13"
 #define RUBY_VERSION_CODE 190
-#define RUBY_RELEASE_CODE 20080612
+#define RUBY_RELEASE_CODE 20080613
 #define RUBY_PATCHLEVEL 0
 
 #define RUBY_VERSION_MAJOR 1
@@ -9,7 +9,7 @@
 #define RUBY_VERSION_TEENY 0
 #define RUBY_RELEASE_YEAR 2008
 #define RUBY_RELEASE_MONTH 6
-#define RUBY_RELEASE_DAY 12
+#define RUBY_RELEASE_DAY 13
 
 #ifdef RUBY_EXTERN
 RUBY_EXTERN const char ruby_version[];