diff --git a/actionmailer/CHANGELOG.md b/actionmailer/CHANGELOG.md
index 5d3f2c328834c..a69d142ad25da 100644
--- a/actionmailer/CHANGELOG.md
+++ b/actionmailer/CHANGELOG.md
@@ -1,3 +1,9 @@
+*   Make ActionMailer::Previews methods class methods. Previously they were
+    instance methods and ActionMailer tries to render a message when they
+    are called.
+
+    *Cristian Bica*
+
 *   Raise an exception when attachments are added after `mail` was called.
     This is a safeguard to prevent invalid emails.
 
diff --git a/actionmailer/lib/action_mailer/preview.rb b/actionmailer/lib/action_mailer/preview.rb
index 33a9faa7e78d9..d9b61453e4e20 100644
--- a/actionmailer/lib/action_mailer/preview.rb
+++ b/actionmailer/lib/action_mailer/preview.rb
@@ -14,7 +14,9 @@ module Previews #:nodoc:
       # :nodoc:
       mattr_accessor :preview_interceptors, instance_writer: false
       self.preview_interceptors = []
+    end
 
+    module ClassMethods
       # Register one or more Interceptors which will be called before mail is previewed.
       def register_preview_interceptors(*interceptors)
         interceptors.flatten.compact.each { |interceptor| register_preview_interceptor(interceptor) }