No rule to make target 'firmware/regulatory.db'

Trying to build Debian for my BeagleV-Fire. According to its readme, ./04_build_linux.sh brought me the following ERROR message:

...
  CC      drivers/base/power/clock_ops.o
  AR      drivers/base/power/built-in.a
  CC      drivers/base/firmware_loader/builtin/main.o
  UPD     drivers/base/firmware_loader/builtin/regulatory.db.gen.S
make[5]: *** No rule to make target 'firmware/regulatory.db', needed by 'drivers/base/firmware_loader/builtin/regulatory.db.gen.o'.  Stop.
make[4]: *** [scripts/Makefile.build:500: drivers/base/firmware_loader/builtin] Error 2
make[3]: *** [scripts/Makefile.build:500: drivers/base/firmware_loader] Error 2
make[2]: *** [scripts/Makefile.build:500: drivers/base] Error 2
make[1]: *** [scripts/Makefile.build:500: drivers] Error 2
make: *** [Makefile:2012: .] Error 2
Build Failed

Can anybody please give me a hand?