diff --git a/digistump-avr/cores/tiny/wiring.h b/digistump-avr/cores/tiny/wiring.h
index 6946ab2..a1ef0c6 100644
--- a/digistump-avr/cores/tiny/wiring.h
+++ b/digistump-avr/cores/tiny/wiring.h
@@ -43,6 +43,7 @@ extern "C"{
 
 #define INPUT 0x0
 #define OUTPUT 0x1
+#define INPUT_PULLUP 0x2
 
 #define true 0x1
 #define false 0x0