Index: kernel/arch/ia32/include/arch/interrupt.h
===================================================================
--- kernel/arch/ia32/include/arch/interrupt.h	(revision 5eae56aa8eba23f4d7a263543454b0317c7727a1)
+++ kernel/arch/ia32/include/arch/interrupt.h	(revision 7a9ef817edf5a2d9985e515dc9b3bbc37af01fc3)
@@ -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