diff --git a/board/usb.h b/board/usb.h
index 38ab981..9095856 100644
--- a/board/usb.h
+++ b/board/usb.h
@@ -46,7 +46,7 @@ USB_OTG_GlobalTypeDef *USBx = USB_OTG_FS;
 
 #define USB_OTG_SPEED_FULL 3
 
-#define MAX_RESP_LEN 0x80
+#define MAX_RESP_LEN 0x40
 uint8_t resp[MAX_RESP_LEN];
 
 typedef union