diff --git a/board/sbc405/sbc405.c b/board/sbc405/sbc405.c
index ef9bce1..cad5873 100644
--- a/board/sbc405/sbc405.c
+++ b/board/sbc405/sbc405.c
@@ -78,7 +78,7 @@
 
 int checkboard (void)
 {
-	unsigned char str[64];
+	char str[64];
 	int i = getenv_r ("serial#", str, sizeof(str));
 
 	puts ("Board: ");