diff --git a/firmware/usb.h b/firmware/usb.h
index 59285e7..06972ba 100644
--- a/firmware/usb.h
+++ b/firmware/usb.h
@@ -25,7 +25,7 @@
 /* ----------------------------- USB interface ----------------------------- */
 /* ------------------------------------------------------------------------- */
 
-PROGMEM char usbHidReportDescriptor[22] = {    /* USB report descriptor */
+PROGMEM const char usbHidReportDescriptor[22] = {    /* USB report descriptor */
     0x06, 0x00, 0xff,              // USAGE_PAGE (Generic Desktop)
     0x09, 0x01,                    // USAGE (Vendor Usage 1)
     0xa1, 0x01,                    // COLLECTION (Application)