Undefined symbol app

Haven't built my watchface for a while, I've upgrade to latest SDK and when I build the new evil thing (whatever that is) I get

BUILD: ERROR: /Users/Rupert/Documents/Data/Rupert/dev/REPOS/ConnectIQ/BigTime/./source/BigTimeApp.mc:30: Undefined symbol "app" detected.

Seems to be this line



return app.getProperty("PROP_FONT");

I have not changed the code for ages. Any idea? Ta