diff --git a/Marlin/src/HAL/AVR/fastio/fastio_AT90USB.h b/Marlin/src/HAL/AVR/fastio/fastio_AT90USB.h
index 2119d168ab..a9af519ff3 100644
--- a/Marlin/src/HAL/AVR/fastio/fastio_AT90USB.h
+++ b/Marlin/src/HAL/AVR/fastio/fastio_AT90USB.h
@@ -363,8 +363,11 @@
 #define AIO7_PWM    0
 #define AIO7_DDR    DDRF
 
-//-- Begin not supported by Teensyduino
-//-- don't use Arduino functions on these pins pinMode/digitalWrite/etc
+//-- 46-47 are not supported by Teensyduino
+//-- Don't use Arduino functions (pinMode, digitalWrite, etc.) on these pins
+#define PIN_E2   46
+#define PIN_E3   47
+
 #define DIO46_PIN   PINE2
 #define DIO46_RPORT PINE
 #define DIO46_WPORT PORTE
@@ -377,10 +380,7 @@
 #define DIO47_PWM   0
 #define DIO47_DDR   DDRE
 
-#define TEENSY_E2   46
-#define TEENSY_E3   47
-
-//-- end not supported by Teensyduino
+//--
 
 #undef PA0
 #define PA0_PIN     PINA0
diff --git a/Marlin/src/HAL/AVR/pinsDebug.h b/Marlin/src/HAL/AVR/pinsDebug.h
index e9bc09a4bf..c833964a29 100644
--- a/Marlin/src/HAL/AVR/pinsDebug.h
+++ b/Marlin/src/HAL/AVR/pinsDebug.h
@@ -377,16 +377,16 @@ void printPinPort(const pin_t pin) {   // print port number
     uint8_t x;
     SERIAL_ECHOPGM("  Port: ");
     #if AVR_AT90USB1286_FAMILY
-      x = (pin == 46 || pin == 47) ? 'E' : digitalPinToPort_DEBUG(pin) + 64;
+      x = (pin == PIN_E2 || pin == PIN_E3) ? 'E' : 'A' + digitalPinToPort_DEBUG(pin) - 1;
     #else
-      x = digitalPinToPort_DEBUG(pin) + 64;
+      x = 'A' + digitalPinToPort_DEBUG(pin) - 1;
     #endif
     SERIAL_CHAR(x);
 
     #if AVR_AT90USB1286_FAMILY
-      if (pin == 46)
+      if (pin == PIN_E2)
         x = '2';
-      else if (pin == 47)
+      else if (pin == PIN_E3)
         x = '3';
       else {
         uint8_t temp = digitalPinToBitMask_DEBUG(pin);
diff --git a/Marlin/src/gcode/config/M43.cpp b/Marlin/src/gcode/config/M43.cpp
index 893607792a..a515acb241 100644
--- a/Marlin/src/gcode/config/M43.cpp
+++ b/Marlin/src/gcode/config/M43.cpp
@@ -79,20 +79,20 @@ inline void toggle_pins() {
         #endif
       );
       #if AVR_AT90USB1286_FAMILY // Teensy IDEs don't know about these pins so must use FASTIO
-        if (pin == TEENSY_E2) {
-          SET_OUTPUT(TEENSY_E2);
+        if (pin == PIN_E2) {
+          SET_OUTPUT(PIN_E2);
           for (int16_t j = 0; j < repeat; j++) {
-            WRITE(TEENSY_E2, LOW);  safe_delay(wait);
-            WRITE(TEENSY_E2, HIGH); safe_delay(wait);
-            WRITE(TEENSY_E2, LOW);  safe_delay(wait);
+            WRITE(PIN_E2, LOW);  safe_delay(wait);
+            WRITE(PIN_E2, HIGH); safe_delay(wait);
+            WRITE(PIN_E2, LOW);  safe_delay(wait);
           }
         }
-        else if (pin == TEENSY_E3) {
-          SET_OUTPUT(TEENSY_E3);
+        else if (pin == PIN_E3) {
+          SET_OUTPUT(PIN_E3);
           for (int16_t j = 0; j < repeat; j++) {
-            WRITE(TEENSY_E3, LOW);  safe_delay(wait);
-            WRITE(TEENSY_E3, HIGH); safe_delay(wait);
-            WRITE(TEENSY_E3, LOW);  safe_delay(wait);
+            WRITE(PIN_E3, LOW);  safe_delay(wait);
+            WRITE(PIN_E3, HIGH); safe_delay(wait);
+            WRITE(PIN_E3, LOW);  safe_delay(wait);
           }
         }
         else