diff --git a/keyboards/helix/rev2/keymaps/default/config.h b/keyboards/helix/rev2/keymaps/default/config.h
index 987c9b0d19..66c9b9e8bd 100644
--- a/keyboards/helix/rev2/keymaps/default/config.h
+++ b/keyboards/helix/rev2/keymaps/default/config.h
@@ -43,7 +43,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 /* Select rows configuration */
 // Rows are 4 or 5
-#define HELIX_ROWS 5
+// #define HELIX_ROWS 5 see ./rules.mk
 
 /* key matrix size */
 // Rows are doubled-up
diff --git a/keyboards/helix/rev2/keymaps/default/rules.mk b/keyboards/helix/rev2/keymaps/default/rules.mk
index 1705579ad8..070785255b 100644
--- a/keyboards/helix/rev2/keymaps/default/rules.mk
+++ b/keyboards/helix/rev2/keymaps/default/rules.mk
@@ -26,8 +26,9 @@ define HELIX_CUSTOMISE_MSG
 endef
 
 # Helix keyboard customize
-# you can edit follows 4 Variables
-#  jp: 以下の4つの変数を必要に応じて編集します。
+# you can edit follows 5 Variables
+#  jp: 以下の5つの変数を必要に応じて編集します。
+HELIX_ROWS = 5              # Helix Rows is 4 or 5
 OLED_ENABLE = no            # OLED_ENABLE
 LED_BACK_ENABLE = no        # LED backlight (Enable WS2812 RGB underlight.)
 LED_UNDERGLOW_ENABLE = no   # LED underglow (Enable WS2812 RGB underlight.)
@@ -41,6 +42,13 @@ LED_ANIMATIONS = yes        # LED animations
 # $(eval $(call HELIX_CUSTOMISE_MSG))
 # $(info )
 
+ifneq ($(strip $(HELIX_ROWS)), 4)
+  ifneq ($(strip $(HELIX_ROWS)), 5)
+    $(error HELIX_ROWS = $(strip $(HELIX_ROWS)) is unexpected value)
+  endif
+endif
+OPT_DEFS += -DHELIX_ROWS=$(strip $(HELIX_ROWS))
+
 ifeq ($(strip $(LED_BACK_ENABLE)), yes)
   RGBLIGHT_ENABLE = yes
   OPT_DEFS += -DRGBLED_BACK