diff --git a/sys/ia64/ia64/clock.c b/sys/ia64/ia64/clock.c
index 06c96c33fa2..41d8dc4c67c 100644
--- a/sys/ia64/ia64/clock.c
+++ b/sys/ia64/ia64/clock.c
@@ -193,7 +193,7 @@ cpu_initclocks()
 
 	itm_reload = (itc_frequency + hz/2) / hz;
 	ia64_set_itm(ia64_get_itc() + itm_reload);
-	ia64_set_itv(255);	/* highest priority class */
+	ia64_set_itv(CLOCK_VECTOR);	/* highest priority class */
 
 	stathz = 128;
 }
diff --git a/sys/ia64/ia64/interrupt.c b/sys/ia64/ia64/interrupt.c
index d59b4bcdec8..7452bca9b2a 100644
--- a/sys/ia64/ia64/interrupt.c
+++ b/sys/ia64/ia64/interrupt.c
@@ -113,7 +113,7 @@ interrupt(u_int64_t vector, struct trapframe *framep)
 		printf("ExtINT interrupt: vector=%ld\n", vector);
 	}
 
-	if (vector == 255) {/* clock interrupt */
+	if (vector == CLOCK_VECTOR) {/* clock interrupt */
 		/* CTR0(KTR_INTR, "clock interrupt"); */
 			
 		cnt.v_intr++;
diff --git a/sys/ia64/ia64/mp_machdep.c b/sys/ia64/ia64/mp_machdep.c
index 391e350f77f..4ef629bdcbe 100644
--- a/sys/ia64/ia64/mp_machdep.c
+++ b/sys/ia64/ia64/mp_machdep.c
@@ -120,7 +120,7 @@ ia64_ap_startup(void)
 
 	/* kick off the clock on this AP */
 	ia64_set_itm(ia64_get_itc() + itm_reload);
-	ia64_set_itv(255);
+	ia64_set_itv(CLOCK_VECTOR);
 	ia64_set_tpr(0);
 	cpu_throw();
 	panic("ia64_ap_startup: cpu_throw() returned");
diff --git a/sys/ia64/include/clock.h b/sys/ia64/include/clock.h
index 65673c086b5..41e3bf6c902 100644
--- a/sys/ia64/include/clock.h
+++ b/sys/ia64/include/clock.h
@@ -11,6 +11,8 @@
 
 #ifdef _KERNEL
 
+#define	CLOCK_VECTOR	254
+
 extern	int	disable_rtc_set;
 extern	int	wall_cmos_clock;
 extern	int	adjkerntz;