diff --git a/ChangeLog b/ChangeLog
index 39078dc836..c358a95ff1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+Tue Dec 21 00:19:50 2010  NAKAMURA, Hiroshi  <nahi@ruby-lang.org>
+
+	* Backported the fix at
+	  Mon Oct  4 09:30:42 2010  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* ext/openssl/lib/openssl/bn.rb (Integer#to_bn): OpenSSL::BN.new
+	  accepts only Strings, so call Integer#to_s(16).
+	  16 is for an optimization. [ruby-dev:42336]
+
 Sat Dec 11 05:48:28 2010  Hidetoshi NAGAI  <nagai@ai.kyutech.ac.jp>
 
 	* ext/tk/lib/multi-tk.rb: infinite loop on method_missing at loading
diff --git a/ext/openssl/lib/openssl/bn.rb b/ext/openssl/lib/openssl/bn.rb
index e7cbf2cfaf..624c13715c 100644
--- a/ext/openssl/lib/openssl/bn.rb
+++ b/ext/openssl/lib/openssl/bn.rb
@@ -29,7 +29,7 @@ end # OpenSSL
 #
 class Integer
   def to_bn
-    OpenSSL::BN::new(self)
+    OpenSSL::BN::new(self.to_s(16), 16)
   end
 end # Integer
 
diff --git a/test/openssl/test_bn.rb b/test/openssl/test_bn.rb
new file mode 100644
index 0000000000..98ceb7dd30
--- /dev/null
+++ b/test/openssl/test_bn.rb
@@ -0,0 +1,12 @@
+require_relative 'utils'
+
+if defined?(OpenSSL)
+
+class OpenSSL::TestBN < Test::Unit::TestCase
+  def test_integer_to_bn
+    assert_equal(999.to_bn, OpenSSL::BN.new(999.to_s(16), 16))
+    assert_equal((2 ** 107 - 1).to_bn, OpenSSL::BN.new((2 ** 107 - 1).to_s(16), 16))
+  end
+end
+
+end