diff --git a/ChangeLog b/ChangeLog
index a9e6b7404e..d7bd7b60f0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Mar 24 22:19:56 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* parse.y (ripper_initialize): filename can not be modified.
+
 Mon Mar 24 15:19:47 2014  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* addr2line.c (rb_dump_backtrace_with_lines): fetch path of the
diff --git a/parse.y b/parse.y
index 492fd3da64..8d3df90b0a 100644
--- a/parse.y
+++ b/parse.y
@@ -11445,9 +11445,11 @@ ripper_initialize(int argc, VALUE *argv, VALUE self)
     parser->eofp = Qfalse;
     if (NIL_P(fname)) {
         fname = STR_NEW2("(ripper)");
+	OBJ_FREEZE(fname);
     }
     else {
         StringValue(fname);
+	fname = rb_str_new_frozen(fname);
     }
     parser_initialize(parser);
 
diff --git a/test/ripper/test_ripper.rb b/test/ripper/test_ripper.rb
index 1d6e8934ef..b582de5163 100644
--- a/test/ripper/test_ripper.rb
+++ b/test/ripper/test_ripper.rb
@@ -26,6 +26,10 @@ class TestRipper::Ripper < Test::Unit::TestCase
 
   def test_filename
     assert_equal '(ripper)', @ripper.filename
+    filename = "ripper"
+    ripper = Ripper.new("", filename)
+    filename.clear
+    assert_equal "ripper", ripper.filename
   end
 
   def test_lineno