diff --git a/src/main.c b/src/main.c
index 85b6605..c0cf429 100644
--- a/src/main.c
+++ b/src/main.c
@@ -40,9 +40,9 @@ int main(void)
 
 	UART_Init(9600);
 
-	for (int i = 1;; i++) {
-		if (i >= 999) i = 1;
-		sprintf(buf, "BOINK #%03d\r\n", i);
+	for (unsigned long i = 1;; i++) {
+		if (i >= 99999) i = 1;
+		sprintf(buf, "BOINK #%05lu\r\n", i);
 		UART_SendString(buf);
 		_delay_ms(3000);
 	}