Disabling Subject on Forum Replies

Is there a way to disable the subject when replying to messages on the forum?

I understand the purpose of it when you're creating a topic but it doesn't seem to serve a purpose for replies and I constantly find myself ( a ) having to make something up when replying or (b) forgetting to put something in the subject and having to edit the reply because it just grabs the first few words of the reply and puts it in the subject.