diff --git a/ChangeLog b/ChangeLog
index d160eec03e..eeaafaea2d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,11 +1,8 @@
-Tue Mar  6 12:03:33 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Sat Apr 14 18:00:59 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
-	* lib/yaml/rubytypes.rb (Exception.yaml_new): fix bug that causes
-	  YAML serialization problem for Exception.
-	  Exception#initialize doesn't use visible instance variable for
-	  the exception message, so call the method with the message.
-	  patched by Jingwen Owen Ou <jingweno AT gmail.com>.
-	  http://github.com/ruby/ruby/pull/41
+	* bignum.c (rb_big2str0): prevent working clone from
+	  GC. [exerb-dev:0578].  patched by MURASE Masamitsu
+	  <masamitsu.murase AT gmail.com> at [exerb-dev:0580]
 
 Fri Mar  2 10:53:01 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
diff --git a/bignum.c b/bignum.c
index 78e95d7925..208cad9063 100644
--- a/bignum.c
+++ b/bignum.c
@@ -772,7 +772,7 @@ rb_big2str0(x, base, trim)
     int base;
     int trim;
 {
-    volatile VALUE t;
+    VALUE t;
     BDIGIT *ds;
     long i, j, hbase;
     VALUE ss;
@@ -847,6 +847,7 @@ rb_big2str0(x, base, trim)
 	    if (trim && i == 0 && num == 0) break;
 	}
     }
+    RB_GC_GUARD(t);
     if (trim) {while (s[j] == '0') j++;}
     i = RSTRING(ss)->len - j;
     if (RBIGNUM(x)->sign) {