diff --git a/firmware/usb_mem.h b/firmware/usb_mem.h
index 06127cc89270083898b39ce7a7e24d63ed9e8109..ca5c25c79110cc9615dbfcf42437c42a2f500cee 100644
--- a/firmware/usb_mem.h
+++ b/firmware/usb_mem.h
@@ -34,8 +34,9 @@
 #include <stdint.h>
 
 typedef struct usb_packet_struct {
-    struct usb_packet_struct *next;
     uint16_t len;
+    uint16_t reserved;
+    struct usb_packet_struct *next;
     uint8_t buf[64];
 } usb_packet_t;