diff --git a/src_main/io_devices/piusb.h b/src_main/io_devices/piusb.h
index aa838ba1..1da1a6da 100755
--- a/src_main/io_devices/piusb.h
+++ b/src_main/io_devices/piusb.h
@@ -76,7 +76,7 @@ public:
 	};
 
 	struct Descriptor {
-		Descriptor() {memset(this, 0, sizeof(Descriptor));}
+		Descriptor() {usb_spec_number = 0; device_class = device_subclass = device_protocol = max_packet_size = 0; id_vendor = id_product = id_device_release = 0; index_manufacturer = index_product = index_serial = 0;}
 		ushort usb_spec_number;
 		uchar device_class;
 		uchar device_subclass;