diff --git a/ChangeLog b/ChangeLog
index c71590bf27..31cac1cb53 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Oct 12 18:18:03 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* file.c (rb_get_path_check): path name must not contain NUL bytes.
+
 Fri Oct 12 16:06:20 2012  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* tool/merger.rb: now can merge revision(s) without --ticket again.
diff --git a/file.c b/file.c
index 6940142653..b27e769f57 100644
--- a/file.c
+++ b/file.c
@@ -184,6 +184,9 @@ rb_get_path_check(VALUE obj, int level)
 	rb_raise(rb_eEncCompatError, "path name must be ASCII-compatible (%s): %s",
 		 rb_enc_name(enc), RSTRING_PTR(tmp));
     }
+
+    StringValueCStr(tmp);
+
     return rb_str_new4(tmp);
 }
 
diff --git a/test/ruby/test_file.rb b/test/ruby/test_file.rb
index f54e440313..41483cee3a 100644
--- a/test/ruby/test_file.rb
+++ b/test/ruby/test_file.rb
@@ -349,4 +349,14 @@ class TestFile < Test::Unit::TestCase
       end
     end
   end
+
+  def test_open_nul
+    Dir.mktmpdir(__method__.to_s) do |tmpdir|
+      path = File.join(tmpdir, "foo")
+      assert_raise(ArgumentError) do
+        open(path + "\0bar", "w") {}
+      end
+      assert_file_not(:exist?, path)
+    end
+  end
 end