diff --git a/lib/usb_dfu.c b/lib/usb_dfu.c
index f65f5d2..7ede937 100644
--- a/lib/usb_dfu.c
+++ b/lib/usb_dfu.c
@@ -247,7 +247,7 @@ static enum usbd_request_return_codes usb_dfu_control_request(usbd_device *usbd_
 					// application data is exceeding enforced flash size for application
 					usb_dfu_status = DFU_STATUS_ERR_ADDRESS;
 					usb_dfu_state = STATE_DFU_ERROR;
-				} else if ((uint32_t)&__application_end < FLASH_BASE || (uint32_t)&__application_beginning + download_offset + download_length >= (uint32_t)(FLASH_BASE + DESIG_FLASH_SIZE * 1024)) {
+				} else if ((uint32_t)&__application_end < FLASH_BASE && (uint32_t)&__application_beginning + download_offset + download_length >= (uint32_t)(FLASH_BASE + DESIG_FLASH_SIZE * 1024)) {
 					// application data is exceeding advertised flash size
 					usb_dfu_status = DFU_STATUS_ERR_ADDRESS;
 					usb_dfu_state = STATE_DFU_ERROR;