diff --git a/usbboot/src/usb_boot_defines.h b/usbboot/src/usb_boot_defines.h
index 801419a..609a02a 100644
--- a/usbboot/src/usb_boot_defines.h
+++ b/usbboot/src/usb_boot_defines.h
@@ -107,7 +107,7 @@ struct fw_args {
 	unsigned char is_busshare;
 
 	/* debug args */
-	unsigned char debug_ops;
+	char debug_ops;
 	unsigned char pin_num;
 	unsigned int  start;
 	unsigned int  size;