diff --git a/src/buspirate.c b/src/buspirate.c
index e765797f..36848179 100644
--- a/src/buspirate.c
+++ b/src/buspirate.c
@@ -857,7 +857,8 @@ static int buspirate_cmd_ascii(struct programmer_t *pgm,
 {
 	char buf[25];
 	char *rcvd;
-	int spi_write, spi_read, i = 0;
+	int i = 0;
+	unsigned int spi_write, spi_read;
 
 	snprintf(buf, sizeof(buf), "0x%02x 0x%02x 0x%02x 0x%02x\n",
 		cmd[0], cmd[1], cmd[2], cmd[3]);