diff --git a/Makefile b/Makefile
index 819440a..6de2ed3 100644
--- a/Makefile
+++ b/Makefile
@@ -1,15 +1,19 @@
 TARGET = ArduinoIO
+
 # The C source files
 SRC = 
+
 # The C++ source files
 PSRC += main.cpp
+PSRC += IOBoard.cpp
 PSRC += $(wildcard helper/*.cpp) 
 PSRC += arduino_core/ArduinoCore-avr/libraries/SPI/src/SPI.cpp
+
 # extra Arduino libraries
 ARDLIBS = 				
 
-EXTRAINCDIRS = arduino_core/ArduinoCore-avr/libraries/SPI/src
-EXTRAINCDIRS = arduino_core/src
+EXTRAINCDIRS += arduino_core/ArduinoCore-avr/libraries/SPI/src
+EXTRAINCDIRS += arduino_core/src
 
 # this line includes the Makefile.base
 include arduino_core/arduino-base.mk