diff --git a/keyboards/helix/serial.c b/keyboards/helix/serial.c
index 5b0a910b10..1b2b875402 100644
--- a/keyboards/helix/serial.c
+++ b/keyboards/helix/serial.c
@@ -17,25 +17,28 @@
 #define _delay_sub_us(x)    __builtin_avr_delay_cycles(x)
 
 // Serial pulse period in microseconds.
-#define SELECT_SERIAL_SPEED 2
-// !!! 以下の3つ組の定義、、通信速度の「高速」、「中速」、「低速」、「超低速」の4パターンで、実測して合わせこみ
-//     選択できるようにしておく。
+#define SELECT_SERIAL_SPEED 1
 #if SELECT_SERIAL_SPEED == 0
+  // Very High speed
+  #define SERIAL_DELAY 4             // micro sec
+  #define READ_WRITE_START_ADJUST 30 // cycles
+  #define READ_WRITE_WIDTH_ADJUST 10 // cycles
+#elif SELECT_SERIAL_SPEED == 1
   // High speed
   #define SERIAL_DELAY 6             // micro sec
   #define READ_WRITE_START_ADJUST 23 // cycles
   #define READ_WRITE_WIDTH_ADJUST 10 // cycles
-#elif SELECT_SERIAL_SPEED == 1
+#elif SELECT_SERIAL_SPEED == 2
   // Middle speed
   #define SERIAL_DELAY 12            // micro sec
   #define READ_WRITE_START_ADJUST 25 // cycles
   #define READ_WRITE_WIDTH_ADJUST 10 // cycles
-#elif SELECT_SERIAL_SPEED == 2
+#elif SELECT_SERIAL_SPEED == 3
   // Low speed
   #define SERIAL_DELAY 24            // micro sec
   #define READ_WRITE_START_ADJUST 25 // cycles
   #define READ_WRITE_WIDTH_ADJUST 10 // cycles
-#elif SELECT_SERIAL_SPEED == 3
+#elif SELECT_SERIAL_SPEED == 4
   // Very Low speed
   #define SERIAL_DELAY 50            // micro sec
   #define READ_WRITE_START_ADJUST 25 // cycles
diff --git a/keyboards/helix/serial.h b/keyboards/helix/serial.h
index 34d3c89603..db3edf8342 100644
--- a/keyboards/helix/serial.h
+++ b/keyboards/helix/serial.h
@@ -44,7 +44,7 @@ bool serial_slave_data_corrupt(void);
 //#define SERIAL_DEBUG_MODE SERIAL_DEBUG_MODE_WATCH_RCVSAMPLE
 //#define SERIAL_DEBUG_MODE SERIAL_DEBUG_MODE_WATCH_BYTEWIDTH
 //#define SERIAL_DEBUG_MODE (SERIAL_DEBUG_MODE_WATCH_RCVSAMPLE|SERIAL_DEBUG_MODE_WATCH_BYTEWIDTH)
-#define SERIAL_DEBUG_MODE SERIAL_DEBUG_MODE_WATCH_SYNC
+//#define SERIAL_DEBUG_MODE SERIAL_DEBUG_MODE_WATCH_SYNC
 //#define SERIAL_DEBUG_MODE (SERIAL_DEBUG_MODE_WATCH_RCVSAMPLE|SERIAL_DEBUG_MODE_WATCH_SYNC)
 //#define SERIAL_DEBUG_MODE SERIAL_DEBUG_MODE_WATCH_IOCHG