diff --git a/Firmware/Marlin_main.cpp b/Firmware/Marlin_main.cpp
index 44dbfb765..2056ad65f 100644
--- a/Firmware/Marlin_main.cpp
+++ b/Firmware/Marlin_main.cpp
@@ -922,7 +922,7 @@ if((eSoundMode==e_SOUND_MODE_LOUD)||(eSoundMode==e_SOUND_MODE_ONCE))
 
 FILE _uartout; //= {0}; Global variable is always zero initialized. No need to explicitly state this.
 
-int uart_putchar(char c, FILE *stream)
+int uart_putchar(char c, FILE *)
 {
 	MYSERIAL.write(c);
 	return 0;
diff --git a/Firmware/lcd.cpp b/Firmware/lcd.cpp
index d6574d4bb..b4d969ce4 100644
--- a/Firmware/lcd.cpp
+++ b/Firmware/lcd.cpp
@@ -221,7 +221,7 @@ static void lcd_begin(uint8_t lines, uint8_t dotsize, uint8_t clear)
 	lcd_escape[0] = 0;
 }
 
-int lcd_putchar(char c, FILE *stream)
+int lcd_putchar(char c, FILE *)
 {
 	lcd_write(c);
 	return 0;
diff --git a/Firmware/uart2.c b/Firmware/uart2.c
index e6d5c3f88..f62ed1f02 100644
--- a/Firmware/uart2.c
+++ b/Firmware/uart2.c
@@ -16,7 +16,7 @@ uint8_t uart2_ibuf[10] = {0, 0};
 FILE _uart2io = {0};
 
 
-int uart2_putchar(char c, FILE *stream)
+int uart2_putchar(char c, FILE *stream __attribute__((unused)))
 {
 	while (!uart2_txready);
 	UDR2 = c; // transmit byte
@@ -25,7 +25,7 @@ int uart2_putchar(char c, FILE *stream)
 	return 0;
 }
 
-int uart2_getchar(FILE *stream)
+int uart2_getchar(FILE *stream __attribute__((unused)))
 {
 	if (rbuf_empty(uart2_ibuf)) return -1;
 	return rbuf_get(uart2_ibuf);