N300 Static IP Bridge Mode

I have an N300 router I'm using in bridge mode to act as an access point. I'd like to give it a static IP because right now its waiting to get an IP from a piece of gear that isn't always turned on, and I don't want to turn it on everytime I want to be able to connect to the router. While in bridge mode, if I select the static ip option and enter an ip and then try to hit save, it says "illegal value." I have to go back to letting if obtain an address. 

Thanks!