diff --git a/actionpack/lib/action_view/render/layouts.rb b/actionpack/lib/action_view/render/layouts.rb
index <HASH>..<HASH> 100644
--- a/actionpack/lib/action_view/render/layouts.rb
+++ b/actionpack/lib/action_view/render/layouts.rb
@@ -65,7 +65,7 @@ module ActionView
         if formats.size == 1
           _find_layout(layout)
         else
-          update_details(:formats => self.formats.first){ _find_layout(layout) }
+          update_details(:formats => [self.formats.first]) { _find_layout(layout) }
         end
       rescue ActionView::MissingTemplate => e
         update_details(:formats => nil) do
Formats should always be an array.