Append html format instead since by default rails will prepend the passed in format and will override in effect

kaminari-core/lib/kaminari/helpers/tags.rb

@@ -26,7 +26,7 @@ module Kaminari
       end
 
       def to_s(locals = {}) #:nodoc:
-        @template.render :partial => partial_path, :locals => @options.merge(locals), :formats => [:html]
+        @template.render :partial => partial_path, :locals => @options.merge(locals), :formats => @template.formats + [:html]
       end
 
       def page_url_for(page)