diff --git a/railties/lib/rails/generators/actions.rb b/railties/lib/rails/generators/actions.rb
index 8677bf283bb66..57abc151d2acf 100644
--- a/railties/lib/rails/generators/actions.rb
+++ b/railties/lib/rails/generators/actions.rb
@@ -104,7 +104,7 @@ def add_source(source, options={})
       # file in config/environments.
       #
       def environment(data=nil, options={}, &block)
-        sentinel = "Rails::Initializer.run do |config|"
+        sentinel = /class [a-z_:]+ < Rails::Application/i
         data = block.call if !data && block_given?
 
         in_root do