diff --git a/drivers/usb/serial/ark3116.c b/drivers/usb/serial/ark3116.c
index ea2175b..fe43712 100644
--- a/drivers/usb/serial/ark3116.c
+++ b/drivers/usb/serial/ark3116.c
@@ -63,7 +63,8 @@
 				 request, requesttype, value, index,
 				 buf, 0x0000001, 1000);
 	if (result)
-		dbg("%03d < %d bytes [0x%02X]", seq, result, buf[0]);
+		dbg("%03d < %d bytes [0x%02X]", seq, result,
+		    ((unsigned char *)buf)[0]);
 	else
 		dbg("%03d < 0 bytes", seq);
 }