diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index 20911513d0..7154dbdc93 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -178,7 +178,7 @@ module ActionMailer #:nodoc:
             type = (File.basename(path).split(".")[1..-2] || []).join("/")
             next if type.empty?
             @parts << Part.new(:content_type => type,
-              :disposition => "inline", :charset => "charset",
+              :disposition => "inline", :charset => charset,
               :body => render_message(File.basename(path).split(".")[0..-2].join('.'), @body))
           end
         end
diff --git a/actionmailer/test/mail_service_test.rb b/actionmailer/test/mail_service_test.rb
index b61565023c..8eb001ab25 100755
--- a/actionmailer/test/mail_service_test.rb
+++ b/actionmailer/test/mail_service_test.rb
@@ -479,7 +479,9 @@ EOF
     mail = TestMailer.create_implicitly_multipart_example(@recipient)
     assert_equal 2, mail.parts.length
     assert_equal "text/html", mail.parts[0].content_type
+    assert_equal "utf-8", mail.parts[0].sub_header("content-type", "charset")
     assert_equal "text/plain", mail.parts[1].content_type
+    assert_equal "utf-8", mail.parts[1].sub_header("content-type", "charset")
   end
 
   def test_html_mail