3 files changed, 3 insertions, 4 deletions
diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index 1e91d62e24..f00a0c8ae0 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -349,8 +349,7 @@ module ActionMailer #:nodoc:
     include AbstractController::Translation
     include AbstractController::AssetPaths
 
-    cattr_reader :protected_instance_variables
-    @@protected_instance_variables = []
+    self.protected_instance_variables = %w(@_action_has_layout)
 
     helper  ActionMailer::MailHelper
     include ActionMailer::OldApi
diff --git a/actionmailer/lib/action_mailer/old_api.rb b/actionmailer/lib/action_mailer/old_api.rb
index 04728cafb0..bfa9499764 100644
--- a/actionmailer/lib/action_mailer/old_api.rb
+++ b/actionmailer/lib/action_mailer/old_api.rb
@@ -8,7 +8,7 @@ module ActionMailer
 
     included do
       extend ActionMailer::AdvAttrAccessor
-      self.protected_instance_variables.concat %w(@parts @mail_was_called)
+      self.protected_instance_variables.concat %w(@parts @mail_was_called @headers)
 
       # Specify the BCC addresses for the message
       adv_attr_accessor :bcc
diff --git a/actionmailer/lib/action_mailer/version.rb b/actionmailer/lib/action_mailer/version.rb
index 27eb6c2b9b..8cf3780fbc 100644
--- a/actionmailer/lib/action_mailer/version.rb
+++ b/actionmailer/lib/action_mailer/version.rb
@@ -3,7 +3,7 @@ module ActionMailer
     MAJOR = 3
     MINOR = 1
     TINY  = 0
-    PRE   = "beta"
+    PRE   = "beta1"
 
     STRING = [MAJOR, MINOR, TINY, PRE].compact.join('.')
   end