diff --git a/Makefile b/Makefile
index 4ed85676..b3de4834 100644
--- a/Makefile
+++ b/Makefile
@@ -1,140 +1,44 @@
+ALL :=
+CLEAN :=
+
 ifeq ($(ERL_EI_INCLUDE_DIR),)
-$(error ERL_EI_INCLUDE_DIR not set. Invoke via mix)
+
+$(warning ERL_EI_INCLUDE_DIR not set. Invoke via mix)
+
+else
+
+$(info Building NIF.)
+ALL += fbos_build_calendar_nif
+CLEAN += fbos_clean_build_calendar_nif
 endif
 
-# Set Erlang-specific compile and linker flags
-ERL_CFLAGS ?= -I$(ERL_EI_INCLUDE_DIR)
-ERL_LDFLAGS ?= -L$(ERL_EI_LIBDIR)
+ifeq ($(SKIP_ARDUINO_BUILD),)
 
-NIF_LDFLAGS += -fPIC -shared
-NIF_CFLAGS ?= -fPIC -O2 -Wall
+FBARDUINO_FIRMWARE_OUT_DIR := $(PWD)/_build
+FBARDUINO_FIRMWARE_SRC_DIR := $(PWD)/c_src/farmbot-arduino-firmware/src
+FBARDUINO_FIRMWARE_BIN_DIR := $(PWD)/priv
+$(info Building Arduino Firmware.)
+ALL += fbos_arduino_firmware
+CLEAN += fbos_clean_arduino_firmware
 
-ifeq ($(CROSSCOMPILE),)
-ifeq ($(shell uname),Darwin)
-NIF_LDFLAGS += -undefined dynamic_lookup
-endif
+else
+$(warning SKIP_ARDUINO_BUILD is set. No arduino assets will be built.)
 endif
 
-NIF=priv/build_calendar.so
-ARDUINO_FW=priv/arduino-firmware.hex
-FARMDUINO_FW=priv/farmduino-firmware.hex
-FARMDUINO_V14_FW=priv/farmduino_k14-firmware.hex
-BLINK_FW=priv/blink.hex
-CLEAR_EEPROM_FW=priv/clear_eeprom.hex
+.PHONY: $(ALL) $(CLEAN) all clean
 
-ARDUINO_INSTALL_DIR ?= $(HOME)/arduino-1.8.5
-ARDUINO_BUILDER=$(ARDUINO_INSTALL_DIR)/arduino-builder
+all: $(ALL)
 
-ARDUINO_HARDWARE_DIR = $(ARDUINO_INSTALL_DIR)/hardware
-ARDUINO_HARDWARE_FLAGS = -hardware $(ARDUINO_HARDWARE_DIR)
+clean: $(CLEAN)
 
-ARDUINO_TOOLS_FLAGS = -tools $(ARDUINO_INSTALL_DIR)/tools-builder \
--tools $(ARDUINO_HARDWARE_DIR)/tools/avr
+fbos_arduino_firmware:
+	cd c_src/farmbot-arduino-firmware && make all FBARDUINO_FIRMWARE_OUT_DIR=$(PWD)/_build FBARDUINO_FIRMWARE_SRC_DIR=$(PWD)/c_src/farmbot-arduino-firmware/src FBARDUINO_FIRMWARE_BIN_DIR=$(PWD)/priv
 
-ARDUINO_LIBS_FLAGS = -built-in-libraries $(ARDUINO_INSTALL_DIR)/libraries
+fbos_clean_arduino_firmware:
+	cd c_src/farmbot-arduino-firmware && make clean FBARDUINO_FIRMWARE_OUT_DIR=$(PWD)/_build FBARDUINO_FIRMWARE_SRC_DIR=$(PWD)/c_src/farmbot-arduino-firmware/src FBARDUINO_FIRMWARE_BIN_DIR=$(PWD)/priv
 
-ARDUINO_PREFS_FLAGS = -prefs=build.warn_data_percentage=75 \
-	-prefs=runtime.tools.avrdude.path=$(ARDUINO_INSTALL_DIR)/hardware/tools/avr \
-	-prefs=runtime.tools.avr-gcc.path=$(ARDUINO_INSTALL_DIR)/hardware/tools/avr
+fbos_build_calendar_nif:
+	make -f c_src/build_calendar/Makefile all ERL_EI_INCLUDE_DIR=$(ERL_EI_INCLUDE_DIR) ERL_EI_LIBDIR=$(ERL_EI_LIBDIR)
 
-ARDUINO_ARCH_FLAGS = -fqbn=arduino:avr:mega:cpu=atmega2560
-ARDUINO_SRC_INO = c_src/farmbot-arduino-firmware/src/src.ino
-ARDUINO_SRC_BLINK_INO = $(ARDUINO_INSTALL_DIR)/examples/01.Basics/Blink/Blink.ino
-ARDUINO_SRC_CLEAR_EEPROM_INO = $(ARDUINO_HARDWARE_DIR)/arduino/avr/libraries/EEPROM/examples/eeprom_clear/eeprom_clear.ino
-
-ARDUINO_BUILD_DIR = $(PWD)/_build/arduino
-ARDUINO_CACHE_DIR = $(PWD)/_build/arduino-cache
-ARDUINO_BUILD_DIR_FLAGS =	-build-path $(ARDUINO_BUILD_DIR) -build-cache	$(ARDUINO_CACHE_DIR)
-
-ARDUINO_BUILD_COMMON = $(ARDUINO_BUILDER) \
-	$(ARDUINO_HARDWARE_FLAGS) \
-	$(ARDUINO_TOOLS_FLAGS) \
-	$(ARDUINO_LIBS_FLAGS) \
-	$(ARDUINO_ARCH_FLAGS) \
-	$(ARDUINO_PREFS_FLAGS) \
-	$(ARDUINO_BUILD_DIR_FLAGS)
-
-ARDUINO_BUILD = $(ARDUINO_BUILD_COMMON) $(ARDUINO_SRC_INO) > /dev/null 2>&1
-BLINK_BUILD = $(ARDUINO_BUILD_COMMON) $(ARDUINO_SRC_BLINK_INO) > /dev/null 2>&1
-CLEAR_EEPROM_BUILD = $(ARDUINO_BUILD_COMMON) $(ARDUINO_SRC_CLEAR_EEPROM_INO) > /dev/null 2>&1
-
-ENV_STATE_FILE=.make_state
-LAST_STATE = $(shell cat $(ENV_STATE_FILE) > /dev/null 2>&1)
-
-ifeq ($(LAST_STATE),)
-$(shell echo $(MIX_TARGET) > .make_state)
-LAST_STATE=""
-endif
-
-ifneq ($(LAST_STATE), $(MIX_TARGET))
-$(shell echo $(MIX_TARGET) > .make_state)
-$(shell rm -f $(NIF))
-endif
-
-all: priv $(NIF) farmbot_arduino_firmware
-
-farmbot_arduino_firmware_build_dirs: $(ARDUINO_BUILD_DIR) $(ARDUINO_CACHE_DIR)
-
-$(ARDUINO_BUILD_DIR):
-	mkdir -p $(ARDUINO_BUILD_DIR)
-
-$(ARDUINO_CACHE_DIR):
-	mkdir -p $(ARDUINO_CACHE_DIR)
-
-farmbot_arduino_firmware: arduino farmduino farmduino_k14 blink clear_eeprom
-
-arduino: farmbot_arduino_firmware_build_dirs $(ARDUINO_FW)
-
-farmduino: farmbot_arduino_firmware_build_dirs $(FARMDUINO_FW)
-
-farmduino_k14: farmbot_arduino_firmware_build_dirs $(FARMDUINO_V14_FW)
-
-blink: farmbot_arduino_firmware_build_dirs $(BLINK_FW)
-
-clear_eeprom: farmbot_arduino_firmware_build_dirs $(CLEAR_EEPROM_FW)
-
-priv:
-	mkdir -p priv
-
-$(NIF): c_src/build_calendar.c
-	$(CC) $(ERL_CFLAGS) $(NIF_CFLAGS) $(ERL_LDFLAGS) $(NIF_LDFLAGS) -o $@ $<
-
-$(ARDUINO_FW):
-	$(info Building arduino fw)
-	@$(shell echo \#define RAMPS_V14 > c_src/farmbot-arduino-firmware/src/Board.h)
-	@rm -rf $(ARDUINO_BUILD_DIR)/*
-	@rm -rf $(ARDUINO_CACHE_DIR)/*
-	@$(ARDUINO_BUILD)
-	@cp $(ARDUINO_BUILD_DIR)/src.ino.hex $@
-
-$(FARMDUINO_FW):
-	$(info Building Farmduino v10 fw)
-	@$(shell echo \#define FARMDUINO_V10 > c_src/farmbot-arduino-firmware/src/Board.h)
-	@rm -rf $(ARDUINO_BUILD_DIR)/*
-	@rm -rf $(ARDUINO_CACHE_DIR)/*
-	@$(ARDUINO_BUILD)
-	@cp $(ARDUINO_BUILD_DIR)/src.ino.hex $@
-
-$(FARMDUINO_V14_FW):
-	$(info Building Farmduino v14 fw)
-	$(shell echo \#define FARMDUINO_V14 > c_src/farmbot-arduino-firmware/src/Board.h)
-	@rm -rf $(ARDUINO_BUILD_DIR)/*
-	@rm -rf $(ARDUINO_CACHE_DIR)/*
-	@$(ARDUINO_BUILD)
-	@cp $(ARDUINO_BUILD_DIR)/src.ino.hex $@
-
-$(BLINK_FW):
-	$(info Building Blink)
-	@$(BLINK_BUILD)
-	@cp $(ARDUINO_BUILD_DIR)/Blink.ino.hex $@
-
-$(CLEAR_EEPROM_FW):
-	$(info Building clear eeprom utility)
-	@$(CLEAR_EEPROM_BUILD)
-	@cp $(ARDUINO_BUILD_DIR)/eeprom_clear.ino.hex $@
-
-clean:
-	$(RM) $(ENV_STATE_FILE)
-	$(RM) $(NIF)
-	rm -rf $(ARDUINO_BUILD_DIR) $(ARDUINO_CACHE_DIR)
-	rm -rf priv/*.hex
+fbos_clean_build_calendar_nif:
+	make -f c_src/build_calendar/Makefile clean ERL_EI_INCLUDE_DIR=$(ERL_EI_INCLUDE_DIR) ERL_EI_LIBDIR=$(ERL_EI_LIBDIR)
diff --git a/c_src/build_calendar/Makefile b/c_src/build_calendar/Makefile
new file mode 100644
index 00000000..0ad99e16
--- /dev/null
+++ b/c_src/build_calendar/Makefile
@@ -0,0 +1,28 @@
+ifeq ($(ERL_EI_INCLUDE_DIR),)
+$(error ERL_EI_INCLUDE_DIR not set. Invoke via mix)
+endif
+
+# Set Erlang-specific compile and linker flags
+ERL_CFLAGS ?= -I$(ERL_EI_INCLUDE_DIR)
+ERL_LDFLAGS ?= -L$(ERL_EI_LIBDIR)
+
+NIF_LDFLAGS += -fPIC -shared
+NIF_CFLAGS ?= -fPIC -O2 -Wall
+
+NIF=priv/build_calendar.so
+
+ifeq ($(CROSSCOMPILE),)
+ifeq ($(shell uname),Darwin)
+NIF_LDFLAGS += -undefined dynamic_lookup
+endif
+endif
+
+.PHONY: all clean
+
+all: $(NIF)
+
+$(NIF): c_src/build_calendar/build_calendar.c
+	$(CC) $(ERL_CFLAGS) $(NIF_CFLAGS) $(ERL_LDFLAGS) $(NIF_LDFLAGS) -o $@ $<
+
+clean:
+	$(RM) $(NIF)
diff --git a/c_src/build_calendar.c b/c_src/build_calendar/build_calendar.c
similarity index 100%
rename from c_src/build_calendar.c
rename to c_src/build_calendar/build_calendar.c
diff --git a/c_src/farmbot-arduino-firmware b/c_src/farmbot-arduino-firmware
index 776f1d6b..100aa67d 160000
--- a/c_src/farmbot-arduino-firmware
+++ b/c_src/farmbot-arduino-firmware
@@ -1 +1 @@
-Subproject commit 776f1d6bbcc7597dc054d8cedf1d082e5c138441
+Subproject commit 100aa67d2f57ff1d6bbcb024c941d10ada73dbca
diff --git a/mix.exs b/mix.exs
index e1ce3121..ccb38996 100644
--- a/mix.exs
+++ b/mix.exs
@@ -84,8 +84,8 @@ defmodule Farmbot.Mixfile do
     case System.get_env("ERL_EI_INCLUDE_DIR") do
       nil ->
         %{
-          "ERL_EI_INCLUDE_DIR" => "#{:code.root_dir()}/usr/include",
-          "ERL_EI_LIBDIR" => "#{:code.root_dir()}/usr/lib",
+          "ERL_EI_INCLUDE_DIR" => Path.join([:code.root_dir(), "usr", "include"]),
+          "ERL_EI_LIBDIR" => Path.join([:code.root_dir(), "usr", "lib"]),
           "MIX_TARGET" => @target
         }