Add Redirect form breaks URLs containing spaces or %20

I'm trying to add a redirect that redirects from "node/1234" to "magazines/Epilepsy Today" I get the following error:

The redirect path magazines/Epilepsy Today is not valid.

If I try to add "magazines/Epilepsy%20Today" it works but then double encodes the % giving %2520.

As a quick way of solving this I manually edited the row in the database to add the space in which works.