diff --git a/src/flash/nor/at32f4xx.c b/src/flash/nor/at32f4xx.c
index 0b1a6f534..644114a39 100644
--- a/src/flash/nor/at32f4xx.c
+++ b/src/flash/nor/at32f4xx.c
@@ -46,6 +46,7 @@
 #define FLASH_MASS_ERASE_TIMEOUT          120000
 
 #define BANK1_BASE_ADDR                   0x08000000
+#define BANK1_EXT_BASE_ADDR               0x1fffe400
 #define BANK2_BASE_ADDR                   0x08080000
 #define BANK2_BASE_ADDR_4M             0x08200000
 #define SPIM_BASE_ADDR                      0x08400000
@@ -167,6 +168,13 @@ static int at32x_get_product_id(struct flash_bank *bank, uint32_t *product_id)
 static int at32x_get_flash_size(struct flash_bank *bank, uint16_t *flash_size_in_kb)
 {
        struct target *target = bank->target;
+
+       if (bank->base == BANK1_EXT_BASE_ADDR)
+       {
+               *flash_size_in_kb = 4;
+               return ERROR_OK;
+       }
+
        int retval;
        retval = target_read_u16(target, AT32_FLASH_SIZE_ADDR, flash_size_in_kb);
        if (retval != ERROR_OK)
@@ -356,7 +364,7 @@ static int at32_get_device_info(struct flash_bank *bank)
                {
                        at32x_info->usd_addr = at32_mcu_type[at32x_info->type_id].usd_addr;
                }
-               if(at32x_info->bank_addr == BANK1_BASE_ADDR)
+               if(at32x_info->bank_addr == BANK1_BASE_ADDR || at32x_info->bank_addr == BANK1_EXT_BASE_ADDR)
                {
                       if(at32x_info->cur_reg_base == 0)
                                at32x_info->cur_reg_base = at32_mcu_type[at32x_info->type_id].flash_bank1_reg;

diff --git a/usr/share/openocd/scripts/target/at32f421xx.cfg b/at32f421xx.cfg
index 3197261..1278514 100644
--- a/usr/share/openocd/scripts/target/at32f421xx.cfg
+++ b/at32f421xx.cfg
@@ -55,9 +55,8 @@ target create $_TARGETNAME cortex_m -endian $_ENDIAN -dap $_CHIPNAME.dap
 $_TARGETNAME configure -work-area-phys 0x20000000 -work-area-size $_WORKAREASIZE -work-area-backup 0
 
 # flash size will be probed
-set _FLASHNAME $_CHIPNAME.bank1
-flash bank $_FLASHNAME $_CHIPNAME 0x08000000 0 0 0 $_TARGETNAME
-
+flash bank $_CHIPNAME.main $_CHIPNAME 0x08000000 0 0 0 $_TARGETNAME
+flash bank $_CHIPNAME.ext $_CHIPNAME 0x1fffe400 0 0 0 $_TARGETNAME
 
 # JTAG speed should be <= F_CPU/6. F_CPU after reset is 8MHz, so use F_JTAG = 1MHz
 adapter speed 5000