diff --git a/Marlin/src/HAL/HAL_AVR/pinsDebug.h b/Marlin/src/HAL/HAL_AVR/pinsDebug.h
index 13c8a42b0..0787076fb 100644
--- a/Marlin/src/HAL/HAL_AVR/pinsDebug.h
+++ b/Marlin/src/HAL/HAL_AVR/pinsDebug.h
@@ -231,10 +231,10 @@ static void err_is_interrupt()   { SERIAL_ECHOPGM("   compare interrupt enabled"
 static void err_prob_interrupt() { SERIAL_ECHOPGM("   overflow interrupt enabled"); }
 static void print_is_also_tied() { SERIAL_ECHOPGM(" is also tied to this pin"); SERIAL_ECHO_SP(14); }
 
-void com_print(uint8_t N, uint8_t Z) {
+inline void com_print(const uint8_t N, const uint8_t Z) {
   const uint8_t *TCCRA = (uint8_t*)TCCR_A(N);
   SERIAL_ECHOPGM("    COM");
-  SERIAL_CHAR('0' + N, 'A' + Z);
+  SERIAL_CHAR('0' + N, Z);
   SERIAL_ECHOPAIR(": ", int((*TCCRA >> (6 - Z * 2)) & 0x03));
 }