-#define SYSMINOR(aoemajor, aoeminor) ((aoemajor) * 10 + (aoeminor))
-#define AOEMAJOR(sysminor) ((sysminor) / 10)
-#define AOEMINOR(sysminor) ((sysminor) % 10)
+#define SYSMINOR(aoemajor, aoeminor) ((aoemajor) * NPERSHELF + (aoeminor))
+#define AOEMAJOR(sysminor) ((sysminor) / NPERSHELF)
+#define AOEMINOR(sysminor) ((sysminor) % NPERSHELF)