From within the ports/nrf directory I'm running:

make BOARD=pca10059

And getting the following error:

Use make V=1 or set BUILD_VERBOSE in your environment to increase build verbosity.
mkdir -p build-pca10059/genhdr
Create build-pca10059/genhdr/pins.h
GEN build-pca10059/genhdr/mpversion.h
GEN build-pca10059/genhdr/moduledefs.h
make: *** No rule to make target 'lib/tinyusb/src/portable/nordic/nrf5x/hal_nrf5x.c', needed by 'build-pca10059/genhdr/qstr.i.last'.  Stop.

Building other targets (i.e. pca10028) works fine. Any ideas?