diff --git a/sys/include/usb.h b/sys/include/usb.h
index 69d895a214..9eb4c1265b 100644
--- a/sys/include/usb.h
+++ b/sys/include/usb.h
@@ -17,20 +17,6 @@
  * @author      Koen Zandberg <koen@bergzand.net>
  */
 
-/* These checks are deliberately outside the include guards, as they depend on
- * a define that only RIOT-internal users set */
-
-#if !(defined(CONFIG_USB_VID) && defined(CONFIG_USB_PID))
-#ifdef USB_H_USER_IS_RIOT_INTERNAL
-/* Reserved for RIOT standard peripherals as per http://pid.codes/1209/7D00/ */
-#define CONFIG_USB_VID (0x1209)
-#define CONFIG_USB_PID (0x7D00)
-#else
-#error Please configure your vendor and product IDs. For development, you may \
-    set CONFIG_USB_VID=0x1209 CONFIG_USB_PID=0x7D01.
-#endif
-#endif
-
 #ifndef USB_H
 #define USB_H
 
@@ -43,6 +29,18 @@ extern "C" {
  * @ingroup config
  * @{
  */
+
+#if !(defined(CONFIG_USB_VID) && defined(CONFIG_USB_PID))
+#ifdef USB_H_USER_IS_RIOT_INTERNAL
+/* Reserved for RIOT standard peripherals as per http://pid.codes/1209/7D00/ */
+#define CONFIG_USB_VID (0x1209)
+#define CONFIG_USB_PID (0x7D00)
+#else
+#error Please configure your vendor and product IDs. For development, you may \
+    set CONFIG_USB_VID=0x1209 CONFIG_USB_PID=0x7D01.
+#endif
+#endif
+
 /**
  * @brief USB peripheral device vendor ID
  *
@@ -132,8 +130,10 @@ extern "C" {
 /**
  * @brief RIOT-internal USB peripheral clearance indicator
  *
- * This define must only be set by RIOT internal users of `usb.h`, and only when
- * they implement peripherals that can be considered default RIOT peripherals.
+ * This define must only be set in compilation units that are RIOT internal,
+ * and only when they implement peripherals that can be considered default RIOT
+ * peripherals.
+ *
  * When this is defined in all uses of `usb.h`, the board can use the
  * 0x1209/0x7D00 VID/PID pair unless explicit configuration using @ref
  * CONFIG_USB_VID and @ref CONFIG_USB_PID say otherwise.