How to disable ARC for a single file in Xcode 5?

I recently downloaded Xcode 5, and it's now my primary IDE. However, I now need to disable Automatic Reference Counting for a single file in my project.

In Xcode 4, I went to the Build Phases tab under my target, and I could double click the on the right side of a row in the Compile Sources section, add -fno-objc-arc to the list of compiler flags, and be off.

In 5, however, the column seems to be unclickable:

So, how do I do this?

Well, I just tried and found that you must had dragged the window to a smaller width. You need to drag it back to show the Compiler Flag column: