ifeq ($(shell uname -s),Linux)
    DU_ARGUMENTS = --block-size=1024 --apparent-size
else ifeq ($(shell uname -s),Darwin)
    DU_ARGUMENTS = -k -A
endif

define disk_usage_KiB
    @printf '%s KiB\n' `du $(DU_ARGUMENTS) $(1) | cut -f1`
endef