diff --git a/lib/rails_api_doc/controller/request/dsl.rb b/lib/rails_api_doc/controller/request/dsl.rb
index <HASH>..<HASH> 100644
--- a/lib/rails_api_doc/controller/request/dsl.rb
+++ b/lib/rails_api_doc/controller/request/dsl.rb
@@ -106,7 +106,7 @@ module RailsApiDoc
         end
 
         def second_argument_is_type?(args)
-          RailsApiDoc::ACCEPTED_TYPES.include?(args[1].to_sym)
+          RailsApiDoc::ACCEPTED_TYPES.include?(args[1]&.to_sym)
         end
 
       end
Fix & to_sym failure