diff --git a/Firmware/Configuration_prusa.h b/Firmware/Configuration_prusa.h
index 4538b226..52ce678f 100644
--- a/Firmware/Configuration_prusa.h
+++ b/Firmware/Configuration_prusa.h
@@ -17,6 +17,7 @@
 
 // Electronics
 #define MOTHERBOARD BOARD_EINSY_0_4a
+#define HAS_SECOND_SERIAL_PORT
 
 
 // Uncomment the below for the E3D PT100 temperature sensor (with or without PT100 Amplifier)
diff --git a/Firmware/ultralcd.cpp b/Firmware/ultralcd.cpp
index 9cd4a932..3d573814 100644
--- a/Firmware/ultralcd.cpp
+++ b/Firmware/ultralcd.cpp
@@ -3908,12 +3908,14 @@ static void lcd_settings_menu()
   else {
 	  MENU_ITEM(function, MSG_TEMP_CALIBRATION_ON, lcd_temp_calibration_set);
   }
+#ifdef HAS_SECOND_SERIAL_PORT
   if (selectedSerialPort == 0) {
 	  MENU_ITEM(function, MSG_SECOND_SERIAL_OFF, lcd_second_serial_set);
   }
   else {
 	  MENU_ITEM(function, MSG_SECOND_SERIAL_ON, lcd_second_serial_set);
   }
+#endif //HAS_SECOND_SERIAL
 
   if (!isPrintPaused && !homing_flag)
 	{
diff --git a/Firmware/variants/1_75mm_MK3-EINY03-E3Dv6full.h b/Firmware/variants/1_75mm_MK3-EINY03-E3Dv6full.h
index 41afcb87..fccd58a9 100644
--- a/Firmware/variants/1_75mm_MK3-EINY03-E3Dv6full.h
+++ b/Firmware/variants/1_75mm_MK3-EINY03-E3Dv6full.h
@@ -17,6 +17,7 @@
 
 // Electronics
 #define MOTHERBOARD BOARD_EINY_0_3a
+#define HAS_SECOND_SERIAL_PORT
 
 
 // Uncomment the below for the E3D PT100 temperature sensor (with or without PT100 Amplifier)
diff --git a/Firmware/variants/1_75mm_MK3-EINY04-E3Dv6full.h b/Firmware/variants/1_75mm_MK3-EINY04-E3Dv6full.h
index 251d01e7..63deeddb 100644
--- a/Firmware/variants/1_75mm_MK3-EINY04-E3Dv6full.h
+++ b/Firmware/variants/1_75mm_MK3-EINY04-E3Dv6full.h
@@ -17,6 +17,7 @@
 
 // Electronics
 #define MOTHERBOARD BOARD_EINY_0_4a
+#define HAS_SECOND_SERIAL_PORT
 
 
 // Uncomment the below for the E3D PT100 temperature sensor (with or without PT100 Amplifier)
diff --git a/Firmware/variants/1_75mm_MK3-EINY10a-E3Dv6full.h b/Firmware/variants/1_75mm_MK3-EINY10a-E3Dv6full.h
index dbc6cb75..be266394 100644
--- a/Firmware/variants/1_75mm_MK3-EINY10a-E3Dv6full.h
+++ b/Firmware/variants/1_75mm_MK3-EINY10a-E3Dv6full.h
@@ -17,6 +17,7 @@
 
 // Electronics
 #define MOTHERBOARD BOARD_EINY_0_4a
+#define HAS_SECOND_SERIAL_PORT
 
 
 // Uncomment the below for the E3D PT100 temperature sensor (with or without PT100 Amplifier)