diff --git a/firmware/main.c b/firmware/main.c
index 39bfe24..18f8fde 100644
--- a/firmware/main.c
+++ b/firmware/main.c
@@ -31,12 +31,12 @@ uint8_t spi_proc()
 
 	if (spi_cs) {
 		if (SPSR & (1 << SPIF)) {
-			SPDR = spdr_next;
 			switch (y) {
-			case Y_MAX:
+			case Y_MAX - 1:
 				spdr_next = 55; // TODO: Vbat
 				break;
 			}
+			SPDR = spdr_next;
 			lcd_set_buffer(x, y, SPDR);
 			if (y == 0) {
 				y = Y_MAX;