diff --git a/converter/adb_usb/keymap.c b/converter/adb_usb/keymap.c
index 60e8c99f..c622dc62 100644
--- a/converter/adb_usb/keymap.c
+++ b/converter/adb_usb/keymap.c
@@ -119,12 +119,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return KEYCODE(layer, row, col);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }
diff --git a/converter/m0110_usb/keymap.c b/converter/m0110_usb/keymap.c
index 5bcb6e67..4dd419d1 100644
--- a/converter/m0110_usb/keymap.c
+++ b/converter/m0110_usb/keymap.c
@@ -203,12 +203,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return KEYCODE(layer, row, col);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }
diff --git a/converter/news_usb/keymap.c b/converter/news_usb/keymap.c
index 19654095..6f30d59c 100644
--- a/converter/news_usb/keymap.c
+++ b/converter/news_usb/keymap.c
@@ -114,12 +114,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return pgm_read_byte(&keymaps[(layer)][(row)][(col)]);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }
diff --git a/converter/ps2_usb/keymap.c b/converter/ps2_usb/keymap.c
index df3a36b7..c97783fa 100644
--- a/converter/ps2_usb/keymap.c
+++ b/converter/ps2_usb/keymap.c
@@ -368,12 +368,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return pgm_read_byte(&keymaps[(layer)][(row)][(col)]);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }
diff --git a/converter/ps2_usb/keymap_jis.c b/converter/ps2_usb/keymap_jis.c
index fcf8a2ab..866ccd91 100644
--- a/converter/ps2_usb/keymap_jis.c
+++ b/converter/ps2_usb/keymap_jis.c
@@ -286,12 +286,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return pgm_read_byte(&keymaps[(layer)][(row)][(col)]);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }
diff --git a/converter/terminal_usb/keymap_102.c b/converter/terminal_usb/keymap_102.c
index 49e1b17c..e9412b28 100644
--- a/converter/terminal_usb/keymap_102.c
+++ b/converter/terminal_usb/keymap_102.c
@@ -197,12 +197,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return pgm_read_byte(&keymaps[(layer)][(row)][(col)]);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }
diff --git a/converter/terminal_usb/keymap_122.c b/converter/terminal_usb/keymap_122.c
index 1b705d1d..79ca11c2 100644
--- a/converter/terminal_usb/keymap_122.c
+++ b/converter/terminal_usb/keymap_122.c
@@ -132,12 +132,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return pgm_read_byte(&keymaps[(layer)][(row)][(col)]);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }
diff --git a/converter/usb_usb/keymap.c b/converter/usb_usb/keymap.c
index 4ab8c8ab..ff166fcf 100644
--- a/converter/usb_usb/keymap.c
+++ b/converter/usb_usb/keymap.c
@@ -240,12 +240,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return pgm_read_byte(&keymaps[(layer)][(row)][(col)]);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }
diff --git a/converter/x68k_usb/keymap.c b/converter/x68k_usb/keymap.c
index 5cd14cb6..90abb396 100644
--- a/converter/x68k_usb/keymap.c
+++ b/converter/x68k_usb/keymap.c
@@ -129,12 +129,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return pgm_read_byte(&keymaps[(layer)][(row)][(col)]);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }
diff --git a/keyboard/IIgs_Standard/keymap.c b/keyboard/IIgs_Standard/keymap.c
index 722c44af..cd33e223 100644
--- a/keyboard/IIgs_Standard/keymap.c
+++ b/keyboard/IIgs_Standard/keymap.c
@@ -131,12 +131,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return KEYCODE(layer, row, col);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }
diff --git a/keyboard/hbkb/keymap.c b/keyboard/hbkb/keymap.c
index 435cf1e9..b89bdf8e 100644
--- a/keyboard/hbkb/keymap.c
+++ b/keyboard/hbkb/keymap.c
@@ -220,12 +220,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return KEYCODE(layer, row, col);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }
diff --git a/keyboard/macway/keymap.c b/keyboard/macway/keymap.c
index aa50ba5c..b7734849 100644
--- a/keyboard/macway/keymap.c
+++ b/keyboard/macway/keymap.c
@@ -184,12 +184,12 @@ uint8_t keymap_get_keycode(uint8_t layer, uint8_t row, uint8_t col)
     return KEYCODE(layer, row, col);
 }
 
-uint8_t keymap_fn_layer(uint8_t fn_bits)
+uint8_t keymap_fn_layer(uint8_t index)
 {
-    return pgm_read_byte(&fn_layer[biton(fn_bits)]);
+    return pgm_read_byte(&fn_layer[index]);
 }
 
-uint8_t keymap_fn_keycode(uint8_t fn_bits)
+uint8_t keymap_fn_keycode(uint8_t index)
 {
-    return pgm_read_byte(&fn_keycode[(biton(fn_bits))]);
+    return pgm_read_byte(&fn_keycode[index]);
 }