diff --git a/ChangeLog b/ChangeLog
index eb20a73827..8418ce81f8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Feb 26 13:26:21 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* eval.c (setup_exception): preserve errinfo across calling #to_s
+	  method on the exception.  [ruby-core:61091] [Bug #9568]
+
 Wed Feb 26 01:29:27 2014  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* string.c (sym_find): Add Symbol.find(str), which returns whether given
diff --git a/eval.c b/eval.c
index 6102cfdc86..a70a7a9cb8 100644
--- a/eval.c
+++ b/eval.c
@@ -511,9 +511,12 @@ setup_exception(rb_thread_t *th, int tag, volatile VALUE mesg, VALUE cause)
 	!rb_obj_is_kind_of(e, rb_eSystemExit)) {
 	int status;
 
+	mesg = e;
 	PUSH_TAG();
 	if ((status = EXEC_TAG()) == 0) {
+	    th->errinfo = Qnil;
 	    e = rb_obj_as_string(e);
+	    th->errinfo = mesg;
 	    if (file && line) {
 		warn_printf("Exception `%s' at %s:%d - %"PRIsVALUE"\n",
 			    rb_obj_classname(th->errinfo), file, line, e);
diff --git a/test/ruby/test_exception.rb b/test/ruby/test_exception.rb
index fc1c209e99..ffcee80ca3 100644
--- a/test/ruby/test_exception.rb
+++ b/test/ruby/test_exception.rb
@@ -78,6 +78,28 @@ class TestException < Test::Unit::TestCase
     assert(!bad)
   end
 
+  def test_errinfo_in_debug
+    bug9568 = EnvUtil.labeled_class("[ruby-core:61091] [Bug #9568]", RuntimeError) do
+      def to_s
+        require '\0'
+      rescue LoadError
+        self.class.to_s
+      end
+    end
+
+    err = EnvUtil.verbose_warning do
+      assert_raise(bug9568) do
+        $DEBUG, debug = true, $DEBUG
+        begin
+          raise bug9568
+        ensure
+          $DEBUG = debug
+        end
+      end
+    end
+    assert_include(err, bug9568.to_s)
+  end
+
   def test_break_ensure
     bad = true
     while true