diff --git a/actionmailer/CHANGELOG b/actionmailer/CHANGELOG
index 8345345a43758c824a60079d1aee3c869f6fa46a..5dc7a33f5544afaa9e539b3c1633a965541ffd55 100644
--- a/actionmailer/CHANGELOG
+++ b/actionmailer/CHANGELOG
@@ -1,5 +1,7 @@
 *2.3.0 [Edge]*
 
+* Fixed RFC-2045 quoted-printable bug #1421 [squadette]
+
 * Fixed that no body charset would be set when there are attachments present #740 [Paweł Kondzior]
 
 
diff --git a/actionmailer/lib/action_mailer/quoting.rb b/actionmailer/lib/action_mailer/quoting.rb
index a2f2c70799f8c36f74a82b342558dafc34fde355..94fa0420023bdcf013fa5c6989763759824aaeb3 100644
--- a/actionmailer/lib/action_mailer/quoting.rb
+++ b/actionmailer/lib/action_mailer/quoting.rb
@@ -12,7 +12,7 @@ def quoted_printable(text, charset)
     # account multi-byte characters (if executing with $KCODE="u", for instance)
     def quoted_printable_encode(character)
       result = ""
-      character.each_byte { |b| result << "=%02x" % b }
+      character.each_byte { |b| result << "=%02X" % b }
       result
     end
 
diff --git a/actionmailer/test/test_helper_test.rb b/actionmailer/test/test_helper_test.rb
index b7f9d9f8d38d0fa436c10aad28c3ada5e7a00ddc..9d22bb26bd7aa37f00d6f097aefe72796b659d6f 100644
--- a/actionmailer/test/test_helper_test.rb
+++ b/actionmailer/test/test_helper_test.rb
@@ -36,7 +36,7 @@ def test_charset_is_utf_8
   end
 
   def test_encode
-    assert_equal "=?utf-8?Q?=0aasdf=0a?=", encode("\nasdf\n")
+    assert_equal "=?utf-8?Q?=0Aasdf=0A?=", encode("\nasdf\n")
   end
 
   def test_assert_emails