1 files changed, 4 insertions, 2 deletions
diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index 42d48fd5a6..03d8760d8f 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -293,7 +293,6 @@ module ActionMailer
           end
           unless @parts.empty?
             @content_type = "multipart/alternative"
-            @charset = nil
             @parts = sort_parts(@parts, @implicit_parts_order)
           end
         end
@@ -432,7 +431,10 @@ module ActionMailer
             m.parts << part
           end
           
-          m.set_content_type(real_content_type, nil, ctype_attrs) if real_content_type =~ /multipart/
+          if real_content_type =~ /multipart/
+            ctype_attrs.delete "charset"
+            m.set_content_type(real_content_type, nil, ctype_attrs)
+          end
         end
 
         @mail = m