diff --git a/makefiles/virtual/mcu_virtual.cpp b/makefiles/virtual/mcu_virtual.cpp
index f3ca93cad..44f086235 100644
--- a/makefiles/virtual/mcu_virtual.cpp
+++ b/makefiles/virtual/mcu_virtual.cpp
@@ -910,6 +910,13 @@ extern "C"
 		}
 		return 0;
 	}
+	
+	uint8_t itp_set_step_mode(uint8_t mode) {return 0;}
+
+	uint32_t mcu_free_micros(void)
+	{
+		return (uint32_t)(mcu_free_micros() % 1000);
+	}
 #ifdef __cplusplus
 }
 #endif
diff --git a/uCNC/src/core/parser.c b/uCNC/src/core/parser.c
index 39ff4b877..a0f05fe73 100644
--- a/uCNC/src/core/parser.c
+++ b/uCNC/src/core/parser.c
@@ -698,19 +698,19 @@ static uint8_t parser_fetch_command(parser_state_t *new_state, parser_words_t *w
 		{
 		case 50:
 			mantissa++;
-			__attribute__((fallthrough));
+			__FALL_THROUGH__
 		case 40:
 			mantissa++;
-			__attribute__((fallthrough));
+			__FALL_THROUGH__
 		case 30:
 			mantissa++;
-			__attribute__((fallthrough));
+			__FALL_THROUGH__
 		case 20:
 			mantissa++;
-			__attribute__((fallthrough));
+			__FALL_THROUGH__
 		case 10:
 			mantissa++;
-			__attribute__((fallthrough));
+			__FALL_THROUGH__
 		case 0:
 			break;
 		default:
@@ -1471,7 +1471,7 @@ uint8_t parser_exec_command(parser_state_t *new_state, parser_words_t *words, pa
 		break;
 	case G92_1: // G92.1
 		memset(g92permanentoffset, 0, sizeof(g92permanentoffset));
-		__attribute__((fallthrough));
+		__FALL_THROUGH__
 		// continue
 	case G92_2: // G92.2
 		memset(parser_parameters.g92_offset, 0, sizeof(parser_parameters.g92_offset));
@@ -1643,7 +1643,7 @@ uint8_t parser_exec_command(parser_state_t *new_state, parser_words_t *words, pa
 			{
 				block_data.spindle = 0;
 			}
-			__attribute__((fallthrough));
+			__FALL_THROUGH__
 		case G1:
 			if (block_data.feed == 0)
 			{
@@ -2136,7 +2136,7 @@ static uint8_t parser_gcode_word(uint8_t code, uint8_t mantissa, parser_state_t
 		{
 			return STATUS_GCODE_UNSUPPORTED_COMMAND;
 		}
-		__attribute__((fallthrough));
+		__FALL_THROUGH__
 #ifdef ENABLE_G39_H_MAPPING
 	case 39:
 #endif
@@ -2220,7 +2220,7 @@ static uint8_t parser_gcode_word(uint8_t code, uint8_t mantissa, parser_state_t
 		{
 			return STATUS_GCODE_UNSUPPORTED_COMMAND;
 		}
-		__attribute__((fallthrough));
+		__FALL_THROUGH__
 	case 49:
 		new_state->groups.tlo_mode = ((code == 49) ? G49 : G43);
 		new_group |= GCODE_GROUP_TOOLLENGTH;
@@ -2270,7 +2270,7 @@ static uint8_t parser_gcode_word(uint8_t code, uint8_t mantissa, parser_state_t
 		{
 			return STATUS_GCODE_UNSUPPORTED_COMMAND;
 		}
-		__attribute__((fallthrough));
+		__FALL_THROUGH__
 #ifndef DISABLE_G10_SUPPORT
 	case 10:
 #endif
@@ -2283,7 +2283,7 @@ static uint8_t parser_gcode_word(uint8_t code, uint8_t mantissa, parser_state_t
 			return STATUS_GCODE_MODAL_GROUP_VIOLATION;
 		}
 		cmd->group_0_1_useaxis = 1;
-		__attribute__((fallthrough));
+		__FALL_THROUGH__
 	case 4:
 	case 53:
 		// convert code within 4 bits without
@@ -2327,10 +2327,10 @@ static uint8_t parser_mcode_word(uint8_t code, uint8_t mantissa, parser_state_t
 	{
 	case 60:
 		code = 5;
-		__attribute__((fallthrough));
+		__FALL_THROUGH__
 	case 30:
 		code = (code & 1) ? 5 : 3;
-		__attribute__((fallthrough));
+		__FALL_THROUGH__
 	case 0:
 	case 1:
 	case 2:
diff --git a/uCNC/src/hal/mcus/avr/mcu_avr.c b/uCNC/src/hal/mcus/avr/mcu_avr.c
index cf795031f..75c642140 100644
--- a/uCNC/src/hal/mcus/avr/mcu_avr.c
+++ b/uCNC/src/hal/mcus/avr/mcu_avr.c
@@ -1273,7 +1273,7 @@ ISR(TWI_vect, ISR_BLOCK)
 	case TW_SR_ARB_LOST_SLA_ACK:
 	case TW_SR_ARB_LOST_GCALL_ACK:
 		index++;
-		__attribute__((fallthrough));
+		__FALL_THROUGH__
 	case TW_SR_STOP: // stop or repeated start condition received
 		// sends the data
 		if (i < I2C_SLAVE_BUFFER_SIZE)
@@ -1294,7 +1294,7 @@ ISR(TWI_vect, ISR_BLOCK)
 	case TW_ST_SLA_ACK:
 	case TW_ST_ARB_LOST_SLA_ACK:
 		i = 0;
-		__attribute__((fallthrough));
+		__FALL_THROUGH__
 	case TW_ST_DATA_ACK: // byte sent, ack returned
 		// copy data to output register
 		TWDR = mcu_i2c_buffer[i++];
diff --git a/uCNC/src/hal/mcus/lpc176x/mcu_lpc176x.c b/uCNC/src/hal/mcus/lpc176x/mcu_lpc176x.c
index 4831af9c0..62c63cd65 100644
--- a/uCNC/src/hal/mcus/lpc176x/mcu_lpc176x.c
+++ b/uCNC/src/hal/mcus/lpc176x/mcu_lpc176x.c
@@ -1237,7 +1237,7 @@ void I2C_ISR(void)
 	case 0x68:
 	case 0x78:
 		index++;
-		__attribute__((fallthrough));
+		__FALL_THROUGH__
 	case 0xA0: // stop or repeated start condition received
 		// sends the data
 		if (i < I2C_SLAVE_BUFFER_SIZE)
@@ -1258,7 +1258,7 @@ void I2C_ISR(void)
 	case 0xA8: // addressed, returned ack
 	case 0xB0: // arbitration lost, returned ack
 		i = 0;
-		__attribute__((fallthrough));
+		__FALL_THROUGH__
 	case 0xB8: // byte sent, ack returned
 		// copy data to output register
 		I2C_REG->I2DAT = mcu_i2c_buffer[i++];
diff --git a/uCNC/src/utils.h b/uCNC/src/utils.h
index e883fae21..514bdb32e 100644
--- a/uCNC/src/utils.h
+++ b/uCNC/src/utils.h
@@ -436,6 +436,12 @@ extern "C"
 #define __TIMEOUT_MS__(timeout) timeout*=1000; __TIMEOUT_US__(timeout)
 #define __TIMEOUT_ASSERT__(timeout) if(timeout < 0)
 
+#if defined(__GNUC__) && __GNUC__ >= 7
+ #define __FALL_THROUGH__ __attribute__ ((fallthrough));
+#else
+ #define __FALL_THROUGH__
+#endif /* __GNUC__ >= 7 */
+
 #ifdef __cplusplus
 }
 #endif