Thread:Project:Support desk/Special characters (+ symbole) in url

How can I overcome the problem of "+" character in my url? I'm trying to request the articles that contain "+" symboles like mathematical titled expressions: A+B=C, but it doesn't work on my site (it was working but I don't know what happened lately).

Instead the "+" is treated as a space " " which is then translated by the wiki as "_" and the result of A+B=C becomes A B=C.

I'm using short urls. Can you help me?