diff --git a/common.mk b/common.mk
index 5b70db94..350558f8 100644
--- a/common.mk
+++ b/common.mk
@@ -53,7 +53,11 @@ ifdef PS2_MOUSE_ENABLE
     OPT_DEFS += -DPS2_MOUSE_ENABLE
 endif
 
-ifdef $(or MOUSEKEY_ENABLE, PS2_MOUSE_ENABLE)
+ifdef MOUSEKEY_ENABLE
+    OPT_DEFS += -DMOUSE_ENABLE
+endif
+
+ifdef PS4_MOUSE_ENABLE
     OPT_DEFS += -DMOUSE_ENABLE
 endif
 
@@ -73,6 +77,11 @@ ifdef KEYMAP_SECTION_ENABLE
     EXTRALDFLAGS = -Wl,-L$(TOP_DIR),-Tldscript_keymap_avr5.x
 endif
 
+ifdef KEYMAP_EX_ENABLE
+    SRC += $(COMMON_DIR)/keymap_ex.c
+    OPT_DEFS += -DKEYMAP_EX_ENABLE
+endif
+
 # Version string
 OPT_DEFS += -DVERSION=$(shell (git describe --always --dirty || echo 'unknown') 2> /dev/null)
 
diff --git a/common/keyboard.c b/common/keyboard.c
index 601e3abe..4ad92eb6 100644
--- a/common/keyboard.c
+++ b/common/keyboard.c
@@ -32,6 +32,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "eeconfig.h"
 #include "mousekey.h"
 #include "backlight.h"
+#include "keymap_ex.h"
 
 
 #ifdef MATRIX_HAS_GHOST
@@ -67,6 +68,10 @@ void keyboard_init(void)
 #ifdef BACKLIGHT_ENABLE
     backlight_init();
 #endif
+
+#ifdef KEYMAP_EX_ENABLE
+    keymap_init();
+#endif
 }
 
 /*
diff --git a/common/keymap_ex.c b/common/keymap_ex.c
new file mode 100644
index 00000000..082e3207
--- /dev/null
+++ b/common/keymap_ex.c
@@ -0,0 +1,102 @@
+/*
+Copyright 2013 Kai Ryu <kai1103@gmail.com>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <avr/pgmspace.h>
+#include <avr/eeprom.h>
+#include "eeconfig.h"
+#include "keymap_ex.h"
+#include "debug.h"
+
+#ifdef KEYMAP_EX_ENABLE
+
+void keymap_init(void) {
+    if (!check_keymap_in_eeprom()) {
+        write_keymap_to_eeprom();
+    }
+}
+
+bool check_keymap_in_eeprom(void) {
+    return false;
+}
+
+void write_keymap_to_eeprom(void) {
+    uint16_t checksum = EECONFIG_MAGIC_NUMBER;
+    const uint16_t *fn_actions = fn_actions_pointer();
+    const uint8_t *keymaps = keymaps_pointer();
+    // write fn_actions
+    if (fn_actions != NULL) {
+        uint16_t size_of_fn_actions = fn_actions_size();
+        for (uint16_t i = 0; i < FN_ACTIONS_SIZE_EX; i++) {
+            uint16_t fn_action = 0;
+            if (i < size_of_fn_actions) {
+                fn_action = pgm_read_word(fn_actions + i);
+            }
+            eeconfig_write_keymap_fn_action(i, fn_action);
+            checksum ^= fn_action;
+        }
+    }
+    // write keymaps
+    if (keymaps != NULL) {
+        uint16_t size_of_keymaps = keymaps_size();
+        for (uint16_t i = 0; i < KEYMAPS_SIZE_EX; i++) {
+            uint8_t keymap = 0;
+            if (i < size_of_keymaps) {
+                keymap = pgm_read_byte(keymaps + i);
+            }
+            eeconfig_write_keymap_key_by_index(i, keymap);
+            uint16_t keymap_word = keymap;
+            if (i & 1) {
+                keymap_word = keymap << 8;
+            }
+            checksum ^= keymap_word;
+        }
+    }
+    // write checksum
+    eeprom_write_word(&((keymap_ex_t*)EECONFIG_KEYMAP_EX)->checksum, checksum);
+}
+
+uint8_t eeconfig_read_keymap_key(uint8_t layer, uint8_t row, uint8_t col) {
+    //return eeprom_read_byte(&((keymap_ex_t*)(EECONFIG_KEYMAP_EX))->keymaps[layer][row][col]);
+    return eeprom_read_byte((void*)(EECONFIG_KEYMAP_KEYMAPS + KEY_OFFSET(layer, row, col)));
+}
+
+void eeconfig_write_keymap_key(uint8_t layer, uint8_t row, uint8_t col, uint8_t key) {
+    //return eeprom_write_byte(&((keymap_ex_t*)(EECONFIG_KEYMAP_EX))->keymaps[layer][row][col], key);
+    return eeprom_write_byte((void*)(EECONFIG_KEYMAP_KEYMAPS + KEY_OFFSET(layer, row, col)), key);
+}
+
+uint8_t eeconfig_read_keymap_key_by_index(uint16_t index) {
+    //return eeprom_read_byte(((keymap_ex_t*)(EECONFIG_KEYMAP_EX)) + index);
+    return eeprom_read_byte((void*)(EECONFIG_KEYMAP_KEYMAPS + index));
+}
+
+void eeconfig_write_keymap_key_by_index(uint16_t index, uint8_t key) {
+    //return eeprom_write_byte(((keymap_ex_t*)(EECONFIG_KEYMAP_EX)) + index, key);
+    return eeprom_write_byte((void*)(EECONFIG_KEYMAP_KEYMAPS + index), key);
+}
+
+uint16_t eeconfig_read_keymap_fn_action(uint8_t index) {
+    //return eeprom_read_word(&((keymap_ex_t*)(EECONFIG_KEYMAP_EX))->fn_actions[index]);
+    return eeprom_read_word((void*)(EECONFIG_KEYMAP_FN_ACTIONS + FN_ACTION_OFFSET(index)));
+}
+
+void eeconfig_write_keymap_fn_action(uint8_t index, uint16_t fn_action) {
+    //return eeprom_write_word(&((keymap_ex_t*)(EECONFIG_KEYMAP_EX))->fn_actions[index], fn_action);
+    return eeprom_write_word((void*)(EECONFIG_KEYMAP_FN_ACTIONS + FN_ACTION_OFFSET(index)), fn_action);
+}
+
+#endif
diff --git a/common/keymap_ex.h b/common/keymap_ex.h
new file mode 100644
index 00000000..b15c3fe1
--- /dev/null
+++ b/common/keymap_ex.h
@@ -0,0 +1,62 @@
+/*
+Copyright 2013 Kai Ryu <kai1103@gmail.com>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef KEYMAP_EX_H
+#define KEYMAP_EX_H
+
+#ifdef KEYMAP_EX_ENABLE
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#define EECONFIG_KEYMAP_EX 0x10
+#define FN_ACTIONS_COUNT 8
+#define KEYMAPS_COUNT 8
+
+typedef struct {
+    uint16_t checksum;
+    uint16_t fn_actions[FN_ACTIONS_COUNT];
+    uint8_t keymaps[KEYMAPS_COUNT][MATRIX_ROWS][MATRIX_COLS];
+} keymap_ex_t;
+
+#define EECONFIG_KEYMAP_CHECKSUM (EECONFIG_KEYMAP_EX)
+#define EECONFIG_KEYMAP_FN_ACTIONS (EECONFIG_KEYMAP_EX + sizeof(uint16_t))
+#define EECONFIG_KEYMAP_KEYMAPS (EECONFIG_KEYMAP_FN_ACTIONS + sizeof(uint16_t) * FN_ACTIONS_COUNT)
+
+#define FN_ACTIONS_SIZE_EX (sizeof(uint16_t) * FN_ACTIONS_COUNT)
+#define KEYMAPS_SIZE_EX (sizeof(uint8_t) * KEYMAPS_COUNT * MATRIX_ROWS * MATRIX_COLS)
+#define FN_ACTION_OFFSET(index) (sizeof(uint16_t) * index)
+#define KEY_OFFSET(layer, row, col) (sizeof(uint8_t) * (layer * MATRIX_ROWS * MATRIX_COLS + row * MATRIX_COLS + col))
+
+void keymap_init(void);
+bool check_keymap_in_eeprom(void);
+void write_keymap_to_eeprom(void);
+uint8_t eeconfig_read_keymap_key(uint8_t layer, uint8_t row, uint8_t col);
+void eeconfig_write_keymap_key(uint8_t layer, uint8_t row, uint8_t col, uint8_t key);
+uint8_t eeconfig_read_keymap_key_by_index(uint16_t index);
+void eeconfig_write_keymap_key_by_index(uint16_t index, uint8_t key);
+uint16_t eeconfig_read_keymap_fn_action(uint8_t index);
+void eeconfig_write_keymap_fn_action(uint8_t index, uint16_t fn_action);
+
+const uint8_t* keymaps_pointer(void);
+const uint16_t* fn_actions_pointer(void);
+uint16_t keymaps_size(void);
+uint16_t fn_actions_size(void);
+
+#endif
+
+#endif