diff --git a/micropython/trezorhal/sdcard.c b/micropython/trezorhal/sdcard.c
index f38d1065..23929c96 100644
--- a/micropython/trezorhal/sdcard.c
+++ b/micropython/trezorhal/sdcard.c
@@ -121,14 +121,24 @@ uint32_t sdcard_read_blocks(uint8_t *dest, uint32_t block_num, uint32_t num_bloc
         return SD_ERROR;
     }
 
-    HAL_SD_ErrorTypedef err = SD_OK;
-
     // check that dest pointer is aligned on a 4-byte boundary
     if (((uint32_t)dest & 3) != 0) {
         return SD_ERROR;
     }
 
-    err = HAL_SD_ReadBlocks_BlockNumber(&sd_handle, (uint32_t*)dest, block_num, SDCARD_BLOCK_SIZE, num_blocks);
-
-    return err;
+    return HAL_SD_ReadBlocks_BlockNumber(&sd_handle, (uint32_t*)dest, block_num, SDCARD_BLOCK_SIZE, num_blocks);
+}
+
+uint32_t sdcard_write_blocks(const uint8_t *src, uint32_t block_num, uint32_t num_blocks) {
+    // check that SD card is initialised
+    if (sd_handle.Instance == NULL) {
+        return SD_ERROR;
+    }
+
+    // check that src pointer is aligned on a 4-byte boundary
+    if (((uint32_t)src & 3) != 0) {
+        return SD_ERROR;
+    }
+
+    return HAL_SD_WriteBlocks_BlockNumber(&sd_handle, (uint32_t*)src, block_num, SDCARD_BLOCK_SIZE, num_blocks);
 }
diff --git a/micropython/trezorhal/sdcard.h b/micropython/trezorhal/sdcard.h
index 071dcf29..ae981c4d 100644
--- a/micropython/trezorhal/sdcard.h
+++ b/micropython/trezorhal/sdcard.h
@@ -12,5 +12,6 @@ bool sdcard_power_on(void);
 void sdcard_power_off(void);
 uint64_t sdcard_get_capacity_in_bytes(void);
 uint32_t sdcard_read_blocks(uint8_t *dest, uint32_t block_num, uint32_t num_blocks);
+uint32_t sdcard_write_blocks(const uint8_t *src, uint32_t block_num, uint32_t num_blocks);
 
 #endif