diff --git a/embed/boardloader/main.c b/embed/boardloader/main.c
index 4d05436829..59f05e4c92 100644
--- a/embed/boardloader/main.c
+++ b/embed/boardloader/main.c
@@ -89,7 +89,7 @@ bool copy_sdcard(void)
     for (int i = 0; i < (HEADER_SIZE + hdr.codelen) / SDCARD_BLOCK_SIZE; i++) {
         sdcard_read_blocks((uint8_t *)buf, i, 1);
         for (int j = 0; j < SDCARD_BLOCK_SIZE / sizeof(uint32_t); j++) {
-            if (HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD, BOOTLOADER_START + i * SDCARD_BLOCK_SIZE + j * sizeof(uint32_t), buf[j]) != HAL_OK) {
+            if (!flash_write_word(BOOTLOADER_START + i * SDCARD_BLOCK_SIZE + j * sizeof(uint32_t), buf[j])) {
                 display_printf("copy failed\n");
                 sdcard_power_off();
                 flash_lock();
diff --git a/embed/bootloader/messages.c b/embed/bootloader/messages.c
index 0f4931905b..3d50ca66ff 100644
--- a/embed/bootloader/messages.c
+++ b/embed/bootloader/messages.c
@@ -1,5 +1,3 @@
-#include STM32_HAL_H
-
 #include <string.h>
 
 #include <pb_decode.h>
@@ -279,7 +277,7 @@ static bool _read_payload(pb_istream_t *stream, const pb_field_t *field, void **
         }
         // write data
         for (int i = 0; i < BUFSIZE / sizeof(uint32_t); i++) {
-            if (HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD, FIRMWARE_START + firmware_flashed + chunk_written + i * sizeof(uint32_t), buf[i]) != HAL_OK) {
+            if (!flash_write_word(FIRMWARE_START + firmware_flashed + chunk_written + i * sizeof(uint32_t), buf[i])) {
                 return false;
             }
         }
diff --git a/embed/extmod/modtrezorconfig/norcow_config.h b/embed/extmod/modtrezorconfig/norcow_config.h
index 49d68833c4..826011f905 100644
--- a/embed/extmod/modtrezorconfig/norcow_config.h
+++ b/embed/extmod/modtrezorconfig/norcow_config.h
@@ -1,10 +1,18 @@
 #if defined TREZOR_STM32
+
 #define NORCOW_STM32 1
-#define NORCOW_START_SECTOR 2
+
+#define NORCOW_START_SECTOR  2
 #define NORCOW_START_ADDRESS 0x08008000
+
 #elif defined TREZOR_UNIX
+
 #define NORCOW_UNIX 1
+
 #define NORCOW_FILE "/var/tmp/trezor.config"
+
 #else
+
 #error Unsupported TREZOR port. Only STM32 and UNIX ports are supported.
+
 #endif
diff --git a/embed/trezorhal/flash.c b/embed/trezorhal/flash.c
index 01f02873fd..1b5436b036 100644
--- a/embed/trezorhal/flash.c
+++ b/embed/trezorhal/flash.c
@@ -45,8 +45,7 @@ void flash_set_option_bytes(void)
 bool flash_unlock(void)
 {
     HAL_FLASH_Unlock();
-    __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_EOP | FLASH_FLAG_OPERR | FLASH_FLAG_WRPERR |
-                           FLASH_FLAG_PGAERR | FLASH_FLAG_PGPERR | FLASH_FLAG_PGSERR);
+    __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_EOP | FLASH_FLAG_OPERR | FLASH_FLAG_WRPERR | FLASH_FLAG_PGAERR | FLASH_FLAG_PGPERR | FLASH_FLAG_PGSERR);
     return true;
 }
 
@@ -80,6 +79,16 @@ bool flash_erase_sectors(int start, int end, void (*progress)(uint16_t val))
     return true;
 }
 
+bool flash_write_byte(uint32_t address, uint8_t data)
+{
+    return HAL_OK == HAL_FLASH_Program(FLASH_TYPEPROGRAM_BYTE, address, data);
+}
+
+bool flash_write_word(uint32_t address, uint32_t data)
+{
+    return HAL_OK == HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD, address, data);
+}
+
 #define FLASH_OTP_LOCK_BASE       0x1FFF7A00U
 #define FLASH_OTP_NUM_BLOCKS      16
 #define FLASH_OTP_BLOCK_SIZE      32
@@ -103,15 +112,15 @@ bool flash_otp_write(uint8_t block, uint8_t offset, const uint8_t *data, uint8_t
     if (!flash_unlock()) {
         return false;
     }
-    HAL_StatusTypeDef ret;
+    bool ret;
     for (uint8_t i = 0; i < datalen; i++) {
-        ret = HAL_FLASH_Program(FLASH_TYPEPROGRAM_BYTE, FLASH_OTP_BASE + block * FLASH_OTP_BLOCK_SIZE + offset + i, data[i]);
-        if (ret != HAL_OK) {
+        ret = flash_write_byte(FLASH_OTP_BASE + block * FLASH_OTP_BLOCK_SIZE + offset + i, data[i]);
+        if (!ret) {
             break;
         }
     }
     flash_lock();
-    return ret == HAL_OK;
+    return ret;
 }
 
 bool flash_otp_lock(uint8_t block)
diff --git a/embed/trezorhal/flash.h b/embed/trezorhal/flash.h
index fb0fcc4145..c589d12d0a 100644
--- a/embed/trezorhal/flash.h
+++ b/embed/trezorhal/flash.h
@@ -24,6 +24,8 @@ bool flash_unlock(void);
 bool flash_lock(void);
 
 bool flash_erase_sectors(int start, int end, void (*progress)(uint16_t val));
+bool flash_write_byte(uint32_t address, uint8_t data);
+bool flash_write_word(uint32_t address, uint32_t data);
 
 bool flash_otp_read(uint8_t block, uint8_t offset, uint8_t *data, uint8_t datalen);
 bool flash_otp_write(uint8_t block, uint8_t offset, const uint8_t *data, uint8_t datalen);
diff --git a/vendor/norcow b/vendor/norcow
index 81c00e0a53..8d2843aeb5 160000
--- a/vendor/norcow
+++ b/vendor/norcow
@@ -1 +1 @@
-Subproject commit 81c00e0a53792c5d2c29895824c861e5d4341737
+Subproject commit 8d2843aeb58f8fd0fc5162a11d5be1e2575776ca