diff --git a/examples/ota_demo/ota/local_ota.c b/examples/ota_demo/ota/local_ota.c
index 42200b8b..724e1caf 100644
--- a/examples/ota_demo/ota/local_ota.c
+++ b/examples/ota_demo/ota/local_ota.c
@@ -73,14 +73,14 @@ static bool OUT_OF_RANGE(uint16 erase_sec)
             spi_size_map == FLASH_SIZE_16M_MAP_512_512 ||
             spi_size_map == FLASH_SIZE_32M_MAP_512_512) {
         start_sec = (system_upgrade_userbin_check() == USER_BIN2) ? 1 : 129;
-        sec_num = 123;
+        sec_num = SYSTEM_BIN_MAP_512_512_MAX_SECTOR;
     } else if (spi_size_map == FLASH_SIZE_16M_MAP_1024_1024 ||
                spi_size_map == FLASH_SIZE_32M_MAP_1024_1024) {
         start_sec = (system_upgrade_userbin_check() == USER_BIN2) ? 1 : 257;
-        sec_num = 251;
+        sec_num = SYSTEM_BIN_MAP_1024_1024_MAX_SECTOR;
     } else {
         start_sec = (system_upgrade_userbin_check() == USER_BIN2) ? 1 : 65;
-        sec_num = 59;
+        sec_num = SYSTEM_BIN_NO_MAP_MAX_SECTOR;
     }
 
     if ((erase_sec >= start_sec) && (erase_sec <= (start_sec + sec_num))) {
@@ -233,14 +233,14 @@ void system_upgrade_init(void)
             spi_size_map == FLASH_SIZE_16M_MAP_512_512 ||
             spi_size_map == FLASH_SIZE_32M_MAP_512_512) {
         user_bin2_start = 129;
-        upgrade->fw_bin_sec_num = 123;
+        upgrade->fw_bin_sec_num = SYSTEM_BIN_MAP_512_512_MAX_SECTOR;
     } else if (spi_size_map == FLASH_SIZE_16M_MAP_1024_1024 ||
                spi_size_map == FLASH_SIZE_32M_MAP_1024_1024) {
         user_bin2_start = 257;
-        upgrade->fw_bin_sec_num = 251;
+        upgrade->fw_bin_sec_num = SYSTEM_BIN_MAP_1024_1024_MAX_SECTOR;
     } else {
         user_bin2_start = 65;
-        upgrade->fw_bin_sec_num = 59;
+        upgrade->fw_bin_sec_num = SYSTEM_BIN_NO_MAP_MAX_SECTOR;
     }
 
     upgrade->fw_bin_sec = (system_upgrade_userbin_check() == USER_BIN1) ? user_bin2_start : user_bin1_start;
diff --git a/include/espressif/upgrade.h b/include/espressif/upgrade.h
index 974f6551..f967c5d5 100644
--- a/include/espressif/upgrade.h
+++ b/include/espressif/upgrade.h
@@ -59,6 +59,10 @@ extern "C" {
 #define UPGRADE_FW_BIN1     0x00    /**< firmware, user1.bin */
 #define UPGRADE_FW_BIN2     0x01    /**< firmware, user2.bin */
 
+#define SYSTEM_BIN_NO_MAP_MAX_SECTOR    58
+#define SYSTEM_BIN_MAP_512_512_MAX_SECTOR  122
+#define SYSTEM_BIN_MAP_1024_1024_MAX_SECTOR 250
+
 /**
   * @brief  Callback of upgrading firmware through WiFi.
   *