diff --git a/Makefile b/Makefile
index e5ed841..5ae9a38 100644
--- a/Makefile
+++ b/Makefile
@@ -81,6 +81,9 @@ endif
 ifeq (,$(AVR_BITCLK))
 	AVR_BITCLK=16
 endif
+ifeq (,$(AVR_PORT))
+	AVR_PORT=usb:
+endif
 
 
 .SILENT:
@@ -183,7 +186,7 @@ $(BASE)/.build/%.o: $(CURDIR)/src/%.txt
 $(BASE)/.build/.%.dep:
 
 avrdude: $(BASE)/bin/$(FINALNAME).hex
-	$(AVRDUDE) -c $(AVR_PROG) -p $(AVR_MCU) -P usb: -B $(AVR_BITCLK) $(AVRDUDE_OPERATIONS) -U flash:w:$(BASE)/bin/$(FINALNAME).hex
+	$(AVRDUDE) -c $(AVR_PROG) -p $(AVR_MCU) -P $(AVR_PORT) -B $(AVR_BITCLK) $(AVRDUDE_OPERATIONS) -U flash:w:$(BASE)/bin/$(FINALNAME).hex
 
 include $(wildcard $(MODULEDEPS))