Can't run Dexter outside of build folder after .ui file refactoring

After the .ui file refactoring, I can no longer run Dexter as "dexter", which is a symbolic link to "~/bau/dexter/bin/dexter".

LANGUAGE=en dexter
Traceback (most recent call last):
  File "~/bin/dexter", line 81, in <module>
    app = DexterApp(datadir, options)
  File "~/bau/dexter/dexter/app.py", line 75, in __init__
    os.path.join(datadir, "ui", "dexter-main.ui"), "dexter")
  File "~/bau/dexter/dexter/SimpleGtkbuilderApp.py", line 30, in __init__
    self.builder.add_from_file(path)
glib.GError: Failed to open file '/usr/share/dexter/ui/dexter-main.ui': No such file or directory

Dexter should look in the folder it *resides* in, not the working directory.