diff --git a/lib/exception_notifier.rb b/lib/exception_notifier.rb
index d12a6af6..150c2493 100644
--- a/lib/exception_notifier.rb
+++ b/lib/exception_notifier.rb
@@ -7,6 +7,7 @@ def self.default_ignore_exceptions
       exceptions << ActiveRecord::RecordNotFound if defined? ActiveRecord
       exceptions << AbstractController::ActionNotFound if defined? AbstractController
       exceptions << ActionController::RoutingError if defined? ActionController
+      exceptions << ActionController::UnknownFormat if defined? ActionController
     end
   end