diff --git a/src/sam3x8e/Makefile b/src/sam3x8e/Makefile
index b7e26fcc..ee144a02 100644
--- a/src/sam3x8e/Makefile
+++ b/src/sam3x8e/Makefile
@@ -29,7 +29,13 @@ $(OUT)klipper.bin: $(OUT)klipper.elf
 	@echo "  Creating hex file $@"
 	$(Q)$(OBJCOPY) -O binary $< $@
 
-flash: $(OUT)klipper.bin
+# Flash rules
+lib/bossac/bin/bossac:
+	@echo "  Building bossac"
+	$(Q)make -C lib/bossac bin/bossac
+
+flash: $(OUT)klipper.bin lib/bossac/bin/bossac
 	@echo "  Flashing $^ to $(FLASH_DEVICE) via bossac"
-	$(Q)stty -F "$(FLASH_DEVICE)" 1200
-	$(Q)bossac -i -p "$(FLASH_DEVICE:/dev/%=%)" -R -e -w -v -b $(OUT)klipper.bin
+	$(Q)if [ -z $(FLASH_DEVICE) ]; then echo "Please specify FLASH_DEVICE"; exit 1; fi
+	$(Q)lib/bossac/bin/bossac -U -p "$(FLASH_DEVICE)" -a -e -w $(OUT)klipper.bin -v -b
+	$(Q)lib/bossac/bin/bossac -p "$(FLASH_DEVICE)" -R