diff --git a/lib/usb/usb_standard.c b/lib/usb/usb_standard.c
index d94ceed9..d927942f 100644
--- a/lib/usb/usb_standard.c
+++ b/lib/usb/usb_standard.c
@@ -129,8 +129,9 @@ static uint16_t build_config_descriptor(usbd_device *usbd_dev,
 		}
 	}
 
-	/* Fill in wTotalLength. */
-	*(uint16_t *)(tmpbuf + 2) = totallen;
+	/* Fill in wTotalLength.
+	 * Note that tmpbuf is sometimes not halfword-aligned */
+	memcpy((tmpbuf + 2), &totallen, sizeof(uint16_t));
 
 	return total;
 }