diff --git a/actionpack/lib/action_dispatch/http/mime_negotiation.rb b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
index be899240153ee..4082770b85006 100644
--- a/actionpack/lib/action_dispatch/http/mime_negotiation.rb
+++ b/actionpack/lib/action_dispatch/http/mime_negotiation.rb
@@ -48,7 +48,7 @@ def formats
         @env["action_dispatch.request.formats"] ||=
           if parameters[:format]
             Array(Mime[parameters[:format]])
-          elsif xhr? || (accept && !accept.include?(?,))
+          elsif xhr? || (accept && accept !~ /,\s*\*\/\*/)
             accepts
           else
             [Mime::HTML]
@@ -87,4 +87,4 @@ def negotiate_mime(order)
       end
     end
   end
-end
\ No newline at end of file
+end