diff --git a/src/flash/nor/stm32f1x.c b/src/flash/nor/stm32f1x.c
index e882d7f79..ab1ef2aef 100644
--- a/src/flash/nor/stm32f1x.c
+++ b/src/flash/nor/stm32f1x.c
@@ -473,7 +473,7 @@ static int stm32x_write_block_async(struct flash_bank *bank, const uint8_t *buff
 
 	/* memory buffer */
 	buffer_size = target_get_working_area_avail(target);
-	buffer_size = MIN(hwords_count * 2, MAX(buffer_size, 256));
+	buffer_size = MIN(hwords_count * 2 + 8, MAX(buffer_size, 256));
 	/* Normally we allocate all available working area.
 	 * MIN shrinks buffer_size if the size of the written block is smaller.
 	 * MAX prevents using async algo if the available working area is smaller