diff --git a/util/nvmutil/nvmutil.c b/util/nvmutil/nvmutil.c
index 5269a025..b99f3a81 100644
--- a/util/nvmutil/nvmutil.c
+++ b/util/nvmutil/nvmutil.c
@@ -378,7 +378,7 @@ static void
 cmd_setmac(void)
 {
 	size_t partnum;
-	int mac_updated = 0;
+	unsigned char mac_updated = 0;
 
 	parse_mac_string();
 	printf("MAC address to be written: %s\n", mac);