Ensure details are frozen after @details_keys lookup. The implementation waits to freeze until the last required moment, to avoid duping hashes.

2 files changed, 2 insertions, 3 deletions

diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index 1dc2d92c43..0519783d02 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -591,7 +591,7 @@ module ActionMailer #:nodoc:
       responses, parts_order = [], nil
 
       if block_given?
-        collector = ActionMailer::Collector.new(self) { render(action_name) }
+        collector = ActionMailer::Collector.new(lookup_context) { render(action_name) }
         yield(collector)
         parts_order = collector.responses.map { |r| r[:content_type] }
         responses  = collector.responses
diff --git a/actionmailer/lib/action_mailer/collector.rb b/actionmailer/lib/action_mailer/collector.rb
index bd4f76bbb6..d03e085e83 100644
--- a/actionmailer/lib/action_mailer/collector.rb
+++ b/actionmailer/lib/action_mailer/collector.rb
@@ -22,8 +22,7 @@ module ActionMailer #:nodoc:
 
     def custom(mime, options={})
       options.reverse_merge!(:content_type => mime.to_s)
-      @context.formats = [mime.to_sym]
-      @context.formats.freeze
+      @context.freeze_formats([mime.to_sym])
       options[:body] = block_given? ? yield : @default_render.call
       @responses << options
     end