diff --git a/sys/dev/usb/controller/xhci.c b/sys/dev/usb/controller/xhci.c
index 4d20770d3f6..f2f362749c8 100644
--- a/sys/dev/usb/controller/xhci.c
+++ b/sys/dev/usb/controller/xhci.c
@@ -2831,7 +2831,7 @@ struct xhci_bos_desc xhci_bosd = {
 		.bLength = sizeof(xhci_bosd.usb2extd),
 		.bDescriptorType = 1,
 		.bDevCapabilityType = 2,
-		.bmAttributes = 2,
+		.bmAttributes[0] = 2,
 	},
 	.usbdcd = {
 		.bLength = sizeof(xhci_bosd.usbdcd),
diff --git a/sys/dev/usb/usb.h b/sys/dev/usb/usb.h
index 59093e5ac83..fb1c8e67776 100644
--- a/sys/dev/usb/usb.h
+++ b/sys/dev/usb/usb.h
@@ -323,7 +323,7 @@ struct usb_devcap_usb2ext_descriptor {
 	uByte	bLength;
 	uByte	bDescriptorType;
 	uByte	bDevCapabilityType;
-	uByte	bmAttributes;
+	uDWord	bmAttributes;
 #define	USB_V2EXT_LPM 0x02
 } __packed;
 typedef struct usb_devcap_usb2ext_descriptor usb_devcap_usb2ext_descriptor_t;