diff --git a/farmbot_firmware/Makefile b/farmbot_firmware/Makefile
index 796961ae..08bfc55e 100644
--- a/farmbot_firmware/Makefile
+++ b/farmbot_firmware/Makefile
@@ -1,6 +1,6 @@
 PREFIX=$(PWD)/priv
-BUILD=$(PWD)/_build
 ARDUINO_SRC_DIR=$(PWD)/c_src/farmbot-arduino-firmware
+BUILD=$(ARDUINO_SRC_DIR)/_build
 
 .PHONY: all clean fbos_arduino_firmware
 
@@ -24,4 +24,4 @@ $(PREFIX):
 	mkdir -p $(PREFIX)
 
 $(BUILD):
-	mkdir -p $(BUILD)
\ No newline at end of file
+	mkdir -p $(BUILD)