diff --git a/Marlin/src/lcd/anycubic_touchscreen.cpp b/Marlin/src/lcd/anycubic_touchscreen.cpp
index 8949b416..066aa830 100755
--- a/Marlin/src/lcd/anycubic_touchscreen.cpp
+++ b/Marlin/src/lcd/anycubic_touchscreen.cpp
@@ -146,6 +146,7 @@ char _conv[8];
 void setup_PowerOffPin()
 {
   #if ENABLED(KNUTWURST_4MAXP2)
+    #define POWER_OFF_PIN 21
     SET_OUTPUT(POWER_OFF_PIN);
     WRITE(POWER_OFF_PIN,HIGH);
   #endif