Index: kernel/arch/ia32/include/interrupt.h
===================================================================
--- kernel/arch/ia32/include/interrupt.h	(revision 0d8269b0ede82319cdf579f85786877a03ae370c)
+++ kernel/arch/ia32/include/interrupt.h	(revision 3296df5ebf486ef213eaea03ce982d78f1997fa9)
@@ -53,4 +53,6 @@
 #define IRQ_KBD       1
 #define IRQ_PIC1      2
+/* NS16550 at COM1 */
+#define IRQ_NS16550   4
 #define IRQ_PIC_SPUR  7
 #define IRQ_MOUSE     12