diff --git a/demo/demo.c b/demo/demo.c
index d77279f0b..b2bbe8f98 100644
--- a/demo/demo.c
+++ b/demo/demo.c
@@ -269,7 +269,7 @@ int main(void)
 			switch (state) {
 				case 1:
 					layoutProgress("WORKING", frame % 41 * 25);
-					pbkdf2_hmac_sha512(pass, passlen, salt, saltlen, 100, seed);
+					pbkdf2_hmac_sha512(pass, passlen, salt, saltlen, 100, seed, 64);
 					usbd_ep_write_packet(usbd_dev, 0x81, seed, 64);
 					break;
 			}